Wound dressing and method of treatment

ABSTRACT

Embodiments disclosed herein are directed to negative pressure treatment systems and wound dressing systems, apparatuses, and methods that may be used for the treatment of wounds. In particular, some embodiments are directed to improved wound dressings comprising a bridge portion connecting two or more portions of an absorbent layer that facilitates trimming of the wound dressing to suitable sizes. Some embodiments provide for trimming the dressing in a gap between two or more portions of an absorbent layer and sealing the exposed portion of dressing after trimming when the dressing is applied to skin surrounding a wound.

PRIORITY CLAIM AND INCORPORATION BY REFERENCE

This application is a continuation of U.S. application Ser. No.16/698,050, filed Nov. 27, 2019, which is a continuation of U.S.application Ser. No. 14/775,494, filed Sep. 11, 2015, now issued as U.S.Pat. No. 10,493,184, issued Dec. 3, 2019, which is a national stageapplication of International Patent Application No. PCT/GB2014/050781,filed Mar. 14, 2014, which claims priority to U.S. ProvisionalApplication Ser. No. 61/800,040, filed Mar. 15, 2013, titled “WOUNDDRESSING AND METHOD OF TREATMENT,” U.S. Provisional Application Ser. No.61/828,604, filed May 29, 2013, titled “WOUND DRESSING AND METHOD OFTREATMENT,” U.S. Provisional Application Ser. No. 61/829,187, filed May30, 2013, titled “WOUND DRESSING AND METHOD OF TREATMENT,” U.S.Provisional Application Ser. No. 61/906,865, filed Nov. 20, 2013, titled“WOUND DRESSING AND METHOD OF TREATMENT,” and U.S. ProvisionalApplication No. 61/907,350, filed Nov. 21, 2013, entitled “WOUNDDRESSING AND METHOD OF TREATMENT,” the entireties of each of which arehereby incorporated by reference. The embodiments disclosed in thisapplication are also related to International Patent Application No.PCT/IB2013/002102, filed Jul. 31, 2013, titled “WOUND DRESSING ANDMETHOD OF TREATMENT, International Patent Application No.PCT/IB2013/002060, filed Jul. 31, 2013, titled “WOUND DRESSING ANDMETHOD OF TREATMENT, and U.S. Patent Publication No. 2011/0282309 A1,published Nov. 17, 2011, titled “WOUND DRESSING AND METHOD OF USE,” theentireties of each of which are hereby incorporated by reference.Embodiments from the incorporated by reference applications may beinterchanged and/or added to any of the embodiments disclosed herein.

FIELD OF THE INVENTION

Embodiments described herein relate generally to apparatuses, systems,and methods for the treatment of wounds, for example using dressings incombination with negative pressure wound therapy, and more particularlyto apparatuses, systems, and methods for sizing a dressing for use intreating a wound.

SUMMARY OF THE INVENTION

Certain embodiments disclosed herein relate to improved wound dressingsthat exhibit enhanced adaptability. Such dressings may have advantagesover prior art dressings which may be more difficult to apply,particularly around lengthy incision sites or irregularly shaped wounds.Also disclosed are improved methods of use and systems for use of thesame, preferably in conjunction with negative pressure wound therapy.

Some embodiments of the dressings described herein may include a backinglayer (also referred to herein as a wound cover or drape), that may bemade of a gas impermeable membrane. As is used herein, the backing layermay be made of a gas impermeable membrane. Such dressings may alsocomprise one or more transmission layers and other layers (such asabsorbent material) positioned beneath the backing layer. For example,one or more transmission layers or other layers may be positioned orenclosed between a backing layer and an optional wound contact layer,for example, sealed therebetween. The transmission layer(s) may be inturn positioned between the backing layer and (optional wound contactlayer and) a wound site over which the dressing is configured to bepositioned, for example sealed therebetween.

A transmission layer as described herein allows transmission of fluidsuch as air, and optionally additionally other gases and liquids, awayfrom a wound site into upper layer(s) of the wound dressing. Atransmission layer also ensures that an open air channel can bemaintained to communicate negative pressure over the wound area evenwhen the dressing is handling substantial amounts of exudates. The layershould remain open under the typical pressures that will be appliedduring negative pressure wound therapy. Preferably, a transmission layerremains open over an area corresponding to the wound site, and therebyensures that the whole wound site sees an equalised negative pressure.Alternatively the transmission layer may comprise one or more specificair paths which remain open, such as in and between bridging portions ofa wound dressing as described further below.

Some examples of materials suitable for a transmission layer include athree dimensional structure, for example, a knitted or woven spacerfabric (for example Baltex 7970 weft knitted polyester), although othermaterials such as foam (e.g., reticulated foam), nonwoven materials(e.g., an acquisition distribution layer as described below) could ofcourse be used. Alternatively or additionally the transmission layer mayincorporate absorbent material and absorb liquid drawn away from thewound under the applied negative pressure.

A transmission layer may comprise voids or may comprise one or morematerials which transmit fluid, or may be a combination thereof. Thetransmission layer may incorporate other functional materials providedthat it is still capable of transmitting negative pressure, andpreferably also liquid fluids. In some embodiments, the transmissionlayer is capable of transmitting wound exudates and other compositionsof matter.

Some embodiments described herein include a trimmable dressing, having amain dressing portion or cell in fluid (e.g., gas) communication withadditional dressing portions or cells. One or more additional portionsor cells may be removed to provide a dressing having a size or shape orprofile or articulation which is to be compatible with a wound or woundsite to be dressed. Preferably portions or cells may be retained toprovide a large surface area, or an elongate main dressing portion isprovided to dress a similarly large surface area or elongate wound, orportions or cells may be removed to dress a correspondingly reducedsurface area or reduced length wound. Preferably one or more additionalportions or cells may be conformed to provide a shaped dressing to dressa similarly shaped wound or to dress a wound incorporating or adjacent aprotrusion such as a fixation device, for example a pin, or such as abody part such as a digit. Preferably one or more additional portions orcells may be conformed to provide a profiled dressing to dress asimilarly profiled wound or wound site, such as a wound located oncomplex body topography. Preferably one or more additional portions orcells may be articulated to dress a similarly articulated wound or woundsite such as a wound located on a joint.

A main dressing portion or portions and additional portions or cells asdescribed herein may be connected by one or more bridge portionsincluding one or more transmission layers as described above.

As is used herein, an exposed portion of transmission layer represents aportion at which the backing layer and optional wound contact layer donot enclose the transmission layer. For example, the backing layer maybe partially absent, and additionally the optional wound contact layermay be partially absent, at which the transmission layer terminates inopen-ended manner. It may be desired to seal such exposed portion oftransmission layer (or exposed portions of other layers). As is usedherein, sealing represents sealing in manner to contain fluid, morepreferably in manner to contain negative pressure.

Exposed portion(s) as hereinbefore defined may be the result of removinga portion of the wound dressing, which may be by any envisaged means,for example cutting the wound dressing or tearing along a weakened line.Composite wound dressings may comprise a border for affixing around awound, about a central wound contact portion. The dressings ashereinbefore defined may include a backing layer and wound contact layerof similar footprint or surface area to the transmission layer or otherlayers enclosed therebetween (i.e. a borderless dressing) or of greaterfootprint or surface area than the transmission layer enclosedtherebetween (i.e. a bordered dressing). Exposed portion(s) ashereinbefore defined result from removing a portion of the wounddressing as hereinbefore defined directly enclosing the transmissionlayer or other layers, for example by cutting into or through thebacking layer and wound contact layer and the transmission layertherebetween.

As is used herein, fluid represents liquid and gas. However it is notintended that “fluid” should encompass “vapour”, a favourable moisturevapour transmission rate (MVTR) being a requirement of dressingsenvisaged herein. The backing layer is impermeable or substantiallyimpermeable to fluids including wound exudate. The backing layer isair-tight or substantially air-tight, whereby a negative pressure may bemaintained at a wound site to which the dressing is applied and sealed,for example with sealant, composition or adhesive material. Woundexudates and other fluids may be contained within the wound site and/ordressing and any collection means associated therewith.

As is used herein, a wound dressing may refer to a composite wounddressing, for example an advanced wound management dressing tailored toinclude specific wound therapy provision selected from management ofwound exudates (e.g., ALLEVYN Gentle Border, DURAFIBER, ALLEVYN Life),infection management (e.g., ACTICOAT, IODOSORB), IV site care (e.g.,IV3000), management of compromised skin about the wound, topicalnegative pressure (“TNP”) (e.g., RENASYS F/AB, PICO, KCI Prevena,Kalypto Medical Inc. NPD1000 Negative Pressure Wound Therapy System),post-operative care such as surgical drapes (e.g., OPSITE), temporarybioskin dressings (e.g., BIOBRANE) and the like, most preferably a TNPdressing. For example, a dressing as described herein may be a wounddressing having a silicone (PDMS) wound contact surface, and is morepreferably a TNP dressing. Known TNP dressings include: Smith & NephewDisposable Kits for TNP such as Smith & Nephew, RENASYS-F/AB, AbdominalDressing Kit; Smith & Nephew, RENASYS-F/P, Foam Dressing Kit With Port;Smith & Nephew, RENASYS-G, Gauze Dressing Kit; Smith & Nephew, PICO™dressing kit; and KCI Kits for TNP including, V.A.C.™ GranuFoamDressings Kits; and the like. Additional dressings and methods oftreating wounds with negative pressure are disclosed in the followingapplications that are hereby incorporated by reference in theirentireties: U.S. application Ser. No. 13/381,885, filed 30 Dec. 2011 andpublished as US2012/0116334; U.S. application Ser. No. 12/886,088, filed20 Sep. 2010 and published as US2011/0213287; U.S. application Ser. No.13/092,042, filed 21 Apr. 2011 and published as US2011/0282309; U.S.application Ser. No. 12/744,277, filed 20 Sep. 2010 and published asUS2011/0028918; U.S. application Ser. No. 12/744,218, filed 20 Sep. 2010and published as US2011/0054421; PCT Publication No. WO2011/000622; PCTPublication No. WO 2011/000621; PCT Publication No. WO2011/135285; PCTPublication No. WO2011/135286; U.S. Pat. Nos. 7,964,766, and 7,615,036

Embodiments of dressings described herein address the problem ofproviding dressings in a range of sizes and shapes to accommodateirregularly shaped wounds and body topography, for example vein harvestwound dressings accommodating variations in height and leg-length ofindividuals, which is impractical both to the manufacturer and to theuser. Embodiments enhance adaptability of existing dressings, includingmore recently introduced multisite dressings such as trilobes andquadrilobes. Certain embodiments enable a portion of a dressing to beremoved to create a main wound dressing of desired size or shape orprofile or articulation, and sealing exposed portion(s) thereof tocontain a negative pressure.

The portion(s) of the wound dressing may be removed to size the mainwound dressing portion for positioning over a wound as hereinbeforedefined, for example an incisional wound, an elongate leg wound, anarcuate incisional wound and the like. Similarly the portion(s) of thewound dressing may be removed to shape the main wound dressing portionfor positioning over a wound as hereinbefore defined, such as a flapwound, over a protruding device such as a fixation device or aprotruding body part, to profile the main wound dressing for positioningover a wound as hereinbefore defined, for example on complex bodytopography, or to articulate the main wound dressing for positioningover a wound as hereinbefore defined for example on a flexing joint.

In one embodiment, a wound treatment apparatus for treatment of a woundsite comprises:

-   -   a backing layer having an upper surface and a lower surface,        otherwise termed a backing sheet having two faces, and defining        a perimeter configured to be positioned over skin surrounding a        wound site;    -   one or more transmission layers configured to be positioned        below the backing layer, or otherwise positioned at or on one        side of one face of the backing layer, the one or more        transmission layers comprising one or more bridging portions        having a smaller width than adjacent portions of the one or more        transmission layers; and    -   a port configured to transmit negative pressure through the        backing layer for the application of topical negative pressure        at the wound site.

In some embodiments, an optional wound contact layer may be provided,with the one or more transmission layers positioned between the backinglayer and the wound contact layer. The one or more transmission layersmay be in direct or indirect contact with a lower surface of the backinglayer. In some embodiments, the one or more transmission layers comprisea first layer comprising a spacer material configured to vertically wickfluid. The one or more transmission layers may further comprise a secondlayer comprising an acquisition distribution material configured tohorizontally wick fluid, the second layer positioned above the firstlayer. One of the first layer and the second layer, or both, may bepresent in the one or more bridging portions. In other embodiments, theone or more transmission layers comprise an acquisition distributionmaterial configured to horizontally wick fluid. In some embodiments, theport may comprise an opening in the backing layer. The port may comprisea port member attached to the backing layer over an opening in thebacking layer. The port member may be sealed to the upper surface of thebacking layer. Some embodiments may further comprise an absorbentmaterial between the backing layer and the one or more transmissionlayers having a similar footprint to that of the one or moretransmission layers. Absorbent material may be present or absent in theone or more bridging portions. Some embodiments of the one or moretransmission layers may comprise an acquisition distribution materialbetween the optional wound contact layer and the absorbent layer havinga similar footprint to that of the absorbent material and/or absorbentlayer. The one or more transmission layers may further comprise a spacermaterial configured to distribute negative pressure, the spacer materialhaving a similar footprint to the acquisition distribution material, thespacer material configured to be positioned beneath the acquisitiondistribution material. The acquisition distribution material may bepresent or absent in the one or more bridging portions.

The one or more transmission layers may have a rectangular shape havinga longitudinal axis extend along its length. The one or moretransmission layers may comprise one or more bridging portions centeredon the longitudinal axis. The one or more transmission layers maycomprise three or more bridging portions centered on the longitudinalaxis. The one or more bridging portions may also be offset from thelongitudinal axis. The one or more bridging portions may have a widththat is less than ⅓ the width of adjacent portions of the one or moretransmission layers. The one or more bridging portions may have a widththat is less than ¼ the width of adjacent portions of the one or moretransmission layers. The one or more bridging portions may have a widththat is less than ⅛ the width of adjacent portions of the one or moretransmission layers. As is used herein, a smaller width represents anarrowing of or constriction in a transmission layer with respect toadjacent portions thereof. The one or more transmission layers may havea T-shape with a bridging portion on each leg of the T. The one or moretransmission layers may have a T-shape with at least one bridgingportion on each leg of the T. The one or more transmission layer maycomprise a plurality of cells each separated by one or more bridgingportions. The one or more transmission layer may comprise a plurality ofcells, and wherein each of the plurality of cells is connected to atleast one adjacent cell by one or more bridging portions, and whereinthe one or more bridging portions may provide for gas communicationbetween adjacent cells.

The wound treatment apparatus may be rolled into a tape which can be cutalong the one or more bridging portions. Cutting along or across thebridging portions may sever adjacent cells.

In another embodiment, a wound treatment apparatus for treatment of awound site comprises:

-   -   a backing layer having an upper surface and a lower surface,        otherwise termed a backing sheet having two faces, and defining        a perimeter configured to be positioned over skin surrounding a        wound site;    -   one or more transmission layers configured to be positioned        beneath the backing layer, or otherwise positioned at or on one        side of one face of the backing layer; and    -   a plurality of ports configured to transmit negative pressure        spaced apart on the backing layer.

In some embodiments, the wound treatment apparatus further comprises anoptional wound contact layer, with the one or more transmission layerspositioned between the backing layer and the wound contact layer. Theone or more transmission layers may be in direct or indirect contactwith a lower surface of the backing layer. In some embodiments, the oneor more transmission layer comprise a first layer of a spacer materialconfigured to vertically wick fluid. The one or more transmission layersmay further comprise a second layer of an acquisition distributionmaterial configured to horizontally wick fluid, the second layerpositioned above the first layer. In other embodiments, the one or moretransmission layers comprise an acquisition distribution materialconfigured to horizontally wick fluid. The wound treatment apparatus maybe configured to be rolled into a tape. The plurality of ports each maycomprise an opening in the backing layer covered with a releasable tab.The one or more transmission layers may comprise one or more bridgingportions having a smaller width than adjacent portions of the one ormore transmission layers. The plurality of ports are spaced apartlengthwise on the backing layer when the wound treatment apparatus isrolled into a tape. The wound treatment apparatus may be used in anydesired length by cutting between adjacent ports.

Some embodiments may further comprise a fluidic connector configured tosupply negative pressure to the port. Some embodiments may furthercomprise a source of negative pressure configured to supply negativepressure through the port. Negative pressure may be established at awound site by means of any one of the plurality of ports, or by means ofmultiple ports of the plurality of ports, the remainder of which mayremain sealed or may be removed with a section of dressing. Someembodiments may further comprise one or more separate or integraladhesive strips or sealing strips configured to seal the backing layerto skin surrounding a wound after the apparatus is cut along or acrossthe one or more bridging portions. The strips may be comprised ofbacking layer material, such as polyurethane or hydrocolloid, orsilicone based material such as OP SITE FLEXIFIX or OPSITE FLEXIFIXGentle.

In another embodiment, a method of treating a wound, or of sizing adressing for use in treating a wound, comprises:

-   -   providing a wound dressing comprising:        -   a backing layer; and        -   one or more transmission layers positioned beneath the            backing layer;    -   removing a portion of the wound dressing to create a main wound        dressing portion with one or more exposed portions;    -   positioning the main wound dressing portion over a wound;    -   sealing the main wound dressing to skin surrounding the wound,        wherein sealing comprises sealing the one or more exposed        portions of the main wound dressing portion; and    -   optionally applying negative pressure to the wound through the        backing layer of the main wound dressing portion.

In some embodiments of the method, the one or more transmission layerscomprise one or more bridging portions having a smaller width thanadjacent portions of the one or more transmission layers. In someembodiments, the one or more transmission layers comprise a first layerof a spacer material configured to vertically wick fluid. The one ormore transmission layers may further comprise a second layer of anacquisition distribution material configured to horizontally wick fluid,the second layer positioned above the first layer. One of the firstlayer and the second layer, or both, may be present in one or morebridging portions. In other embodiments, the one or more transmissionlayers comprise an acquisition distribution material configured tohorizontally wick fluid. A portion of the wound dressing may be removedalong at least one of the one or more bridging portions. In someembodiments, removing a portion of the wound dressing comprises cuttingthe wound dressing across at least one of the one or more bridgingportions. At least a portion of the wound dressing may comprise pre-cutscore marks to facilitate removing of the portion of wound dressing. Thedressing may comprise a plurality of openings in the backing layercovered with a releasable tab, and negative pressure may be applied tothe backing layer through one of the openings. The dressing may comprisea plurality of openings in the backing layer covered with a releasabletab, and negative pressure may be applied to the backing layer throughtwo or more of the openings. In some embodiments, the wound dressingfurther comprises an optional wound contact layer, wherein thetransmission layer is positioned between the backing layer and the woundcontact layer.

The portions of the wound dressing may be removed to size the main wounddressing portion for positioning over an incisional wound. The portionsof the wound dressing may be removed to size the main wound dressingportion for positioning over an elongate leg wound. The portions of thewound dressing may be removed to size the main wound dressing portionfor positioning over an arcuate incisional wound.

In another embodiment, a method of treating a wound, or for sizing adressing for use in treating a wound, is provided, comprising:

-   -   providing a wound dressing comprising a backing layer, one or        more transmission layers beneath the backing layer, and a        plurality of spaced apart openings in the backing layer each        covered with a releasable tab;    -   removing a portion of the wound dressing, the removed portion        comprising at least one opening in the backing layer covered        with a releasable tab;    -   positioning the removed portion of the wound dressing over a        wound; and    -   applying negative pressure through at least one opening in the        backing layer after a releasable tab has been removed.

In further embodiments, the wound dressing may be configured into aroll, and the method may further comprise unrolling a portion of thewound dressing from the roll and removing a portion of the wounddressing from the roll.

In another embodiment, a wound treatment apparatus for treatment of awound site comprises:

-   -   a backing layer having an upper surface and a lower surface,        otherwise termed a backing sheet having two faces, and defining        a perimeter configured to be positioned over skin surrounding a        wound site;    -   one or more transmission layers configured to be positioned        below the backing layer or otherwise positioned at or on one        side of one face of the backing layer; and    -   one or more ports configured to transmit negative pressure        through the backing layer for the application of topical        negative pressure at the wound site;    -   wherein the apparatus comprises a plurality of cells or regions        separated by one or more trimmable portions.        This embodiment may incorporate features relating to previous        embodiments hereinabove or hereinbelow. Trimmable portions may        be selected from one or more bridging portions, as herein before        or hereinbelow, and from portions intermediate multiple ports,        each port corresponding to a separate negative pressure module.

In some embodiments, the plurality of cells forms a plurality ofrepeating negative pressure treatment modules. In one embodiment, one ormore of the modules can be removed and the removed module(s) cansubsequently be used to provide negative pressure to the wound site. Inanother embodiment, one or more modules can be removed and the remainingmodule(s) can subsequently be used to provide negative pressure to thewound site. In further embodiments, the trimmable portions may have amaximum width greater than or equal to the width of the absorbent padportion, or otherwise 50 mm (or approximately 50 mm), 40 mm (orapproximately 40 mm), 30 mm (or approximately 30 mm), 20 mm (orapproximately 20 mm), or even 15 mm (or approximately 15 mm). In someembodiments, the trimmable portion may be from 10 mm to 20 mm (orapproximately 10 mm to approximately 20 mm). In some embodiments, thecross-sectional area of a trimmable portion may be 2 mm² orapproximately 2 mm², or more. The cross-sectional area can vary based onthe transmission material used in the trimmable portion. Examplematerials having clinically appropriate transmission properties atvarious dimensions are described below with respect to FIGS. 15A-16C.The one or more trimmable portions may comprise one or more bridgingportions having a smaller width as compared to the width of an adjacentcell or region. For example, the bridging portion may have a maximumwidth of ⅛, ¼, or ⅓ (or approximately ⅛, ¼, or ⅓) of a width of anadjacent cell or region. In some embodiments, the one or moretransmission layers comprise a first layer of a spacer materialconfigured to vertically wick fluid. The one or more transmission layersmay further comprise a second layer of an acquisition distributionmaterial configured to horizontally wick fluid, the second layerpositioned above the first layer. One of the first layer and the secondlayer, or both, may be present in the one or more trimmable portions. Inother embodiments, the one or more transmission layers comprise anacquisition distribution material configured to horizontally wick fluid.The plurality of cells or regions may comprise an absorbent material,the absorbent material positioned between the one or more transmissionlayers and the backing layer. The one or more trimmable portions maycomprise an absorbent material, the absorbent material positionedbetween the one or more transmission layers and the backing layer. Inother embodiments, no absorbent material is positioned between the oneor more transmission layers and the backing layer. Some embodiments ofthe one or more transmission layers may comprise an acquisitiondistribution material having a similar footprint to the absorbentmaterial, the acquisition distribution material configured to bepositioned beneath the absorbent material. The one or more transmissionlayers may further comprise a spacer material configured to distributenegative pressure, the spacer material having a similar footprint to theacquisition distribution material, the spacer material configured to bepositioned beneath the acquisition distribution material. The one ormore transmission layers can comprise an open-cell reticulated foam. Theone or more transmission layers can be configured to experience lessthan a threshold pressure differential across a length of the one ormore transmission layers. The one or more transmission layers can beconfigured with a threshold level of resiliency, such that, aftercompression from an initial height, the one or more transmission layersreturns to a threshold percentage of the initial height. The one or moretransmission layers can be configured with a threshold level ofresiliency, such that, after compression from an initial height, the oneor more transmission layers returns to a threshold second height.

The one or more ports may each comprise an opening in the backing layercovered with a releasable tab, and negative pressure may be applied tothe backing layer through at least one of the openings. Some embodimentsmay comprise multiple ports configured to transmit negative pressurethrough the backing layer, each port corresponding to a separatenegative pressure treatment module. Some embodiments may furthercomprise a wound contact layer configured to be positioned beneath theone or more transmission layers, the wound contact layer furtherconfigured to seal to the backing layer around the perimeter.

In some embodiments, the plurality of cells may be approximately thesame size, approximately square, and configured in a grid. In otherembodiments, the plurality of cells may be configured in a T-shape. Inother embodiments, the plurality of cells may be configured into a roll.In other embodiments, the plurality of cells may be configured in alinear arrangement. In some embodiments, each of the plurality of cellsmay be configured with one of the one or more ports. In otherembodiments, at least two of the plurality of cells may be eachconfigured with one of the one or more ports. The apparatus may furthercomprise a source of negative pressure connected to some or all of theone or more ports. In some embodiments, the dressing may comprise anexposed portion of one or more transmission layers. The exposed portionmay be sealed with a sealant or adhesive material.

In another embodiment, a wound treatment apparatus for treatment of awound site comprises:

-   -   a backing layer having an upper surface and a lower surface,        otherwise termed a backing sheet having two faces, and defining        a perimeter configured to be positioned over skin surrounding a        wound site;    -   at least one absorbent pad portion comprising:        -   an absorbent layer positioned below the backing layer or            otherwise positioned at or on one side of one face of the            backing layer, and        -   one or transmission layers positioned below the absorbent            layer or otherwise positioned at or on one side of one face            of the absorbent layer;    -   at least one trimmable bridging portion comprising the one or        more transmission layers positioned below the backing layer.        Optionally, a wound contact layer may be positioned below the        one or more transmission layers, wherein the wound contact layer        is sealed to the backing layer along a perimeter of the backing        layer and the wound contact layer. The trimmable bridging        portion in some embodiments may also include a portion of        absorbent layer. In other embodiments, no absorbent layer is        present in the bridging portion. In some embodiments, a width of        the one or more transmission layers in the bridging portion is        less than a width of the one or more transmission layers in the        absorbent pad portion. In other embodiments, the width of the        one or more transmission layers in the bridging portion is the        same as the width of the one or more transmission layers in the        absorbent pad portion

In another embodiment, a wound treatment apparatus for treatment of awound site comprises:

-   -   a backing layer having an upper surface and a lower surface,        otherwise termed a backing sheet having two faces, and defining        a perimeter configured to be positioned over skin surrounding a        wound site;    -   a first portion underneath the backing layer, or otherwise        positioned at or on one side of one face of the backing layer,        the first portion comprising at least one material layer        configured to transmit negative pressure to the wound site; and    -   a bridging portion underneath the backing layer, or otherwise        positioned at or on one side of one face of the backing layer,        the bridging portion comprising at least one material layer        configured to transmit negative pressure from the first portion        through the bridging portion.        The backing layer may be configured to maintain negative        pressure over the wound site. In some embodiments, the at least        one material layer in the bridging portion has a smaller        dimension or a different material structure than a corresponding        dimension or material structure of the first portion.        Optionally, a wound contact layer may be positioned below the        backing layer, wherein the wound contact layer is sealed to the        backing layer along a perimeter of the backing layer.

In some embodiments, the at least one material layer of the firstportion comprises one or more of a transmission layer such asreticulated open-cell foam, woven material, non-woven material, 3D knitfabric, Baltex 7970 weft knitted polyester, acquisition distributionmaterial, DryWeb TDL2, SlimCore TL4, or the like. The at least onematerial of the first portion can additionally or alternatively comprisean absorbent layer, for example a superabsorbent pad comprisingcellulose fibers and superabsorbent particles, MH460.101, ALLEVYN™ foam,Freudenberg 114-224-4, or Chem-Posite™ 11C-450. In some embodiments, thebridging portion comprises at least one material layer comprising one ormore of reticulated open-cell foam, woven material, non-woven material,3D knit fabric, Baltex 7970 weft knitted polyester, acquisitiondistribution material, DryWeb TDL2, SlimCore TL4, or the like. In someembodiments, the at least one material layer of the bridging portionshould transmit a negative pressure of at least −40 mmHg against a setpoint in the range −60 to −200 mmHg with an air leak of 50 cc/minute. Insome embodiments, the at least one material layer of the bridgingportion should experience a pressure differential of approximately −25mmHg or less (that is, closer to zero) at a set point of −200 mmHg withan air leak of 50 cc/minute over an approximately 20 mm±1 mm distance.In other embodiments, the at least one material layer of the bridgingportion should experience a pressure differential of approximately −5mmHg or less (that is, closer to zero) at a set point of −200 mmHg withan air leak of 50 cc/minute over an approximately 20 mm±1 mm distance.In some embodiments, the at least one material layer of the bridgingportion has a height, in an uncompressed state, of at least 1 mm (orapproximately 1 mm), at least 3 mm (or approximately 3 mm), at least 4mm (or approximately 4 mm), or at least 5 mm (or approximately 5 mm),and a width of at least 1 mm (or approximately 1 mm), or at least 2 mm(or approximately 2 mm), at least 3 mm (or approximately 3 mm), at least4 mm (or approximately 4 mm), or at least 5 mm (or approximately 5 mm).In some embodiments, the at least one material layer of the bridgingportion has a maximum height, in an uncompressed state, of 9 mm (orapproximately 9 mm) for purposes of being more easily re-sealable whencut. In some embodiments in which the dressing is sealed with a sealant,the at least one material layer can be resilient to compression suchthat a height of a sealed portion, in a compressed state, issubstantially the same as the height of the sealed portion in anuncompressed state. In one embodiment, the at least one material layerof the bridging portion comprises a spacer material having a height ofat least 2 mm (or approximately 2 mm) and a width of at least 1 mm (orapproximately 1 mm). In one embodiment, the at least one material layerof the bridging portion comprises a reticulated open-cell foam having aheight of at least approximately 5 mm and a width of at leastapproximately 3 mm, which, when wet, may experience a pressuredifferential of −8.9 (or approximately −8.9) mmHg. In anotherembodiment, the at least one material layer of the bridging portioncomprises an acquisition distribution layer (e.g., SlimCore TL4) havinga height of at least approximately 2 mm and a width of at leastapproximately 4 mm. Such dimensions can represent an uncompresseddimension of the material layer of the bridging portion. In oneembodiment, the at least one material layer of the bridging portion isnot compressible.

In some embodiments, the bridging portion comprises the same layer(s) asthe first portion. In other embodiments, the bridging portion comprisesfewer layers than the first portion. In some embodiments, the layer(s)in the bridging portion have a smaller width than the layer(s) in thefirst portion. In some embodiments, the layer(s) in the bridging portionhave a dimension that is smaller than the layer(s) in the first portion(for example, the individual or combined height of the layer(s) in thebridging portion is smaller than the height of the layer(s) in the firstportion. In other embodiments, the layer(s) in the bridging portion havethe same width as the layer(s) in the first portion. In someembodiments, the bridging portion connects the first portion to anadjacent portion having a similar layered construction and/or width asthe first portion. In some embodiments, there are multiple bridgingportions that may connect a first portion to multiple adjacent portions,or may connect between multiple adjacent portions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a wound treatment system;

FIGS. 2A-2D illustrate the use and application of an embodiment of awound treatment system onto a patient;

FIG. 3A illustrates an embodiment of a wound dressing in cross-section;

FIG. 3B illustrates another embodiment of a wound dressing incross-section;

FIG. 3C illustrates another embodiment of a wound dressing incross-section;

FIG. 4A illustrates an exploded view of an embodiment of a wounddressing;

FIG. 4B illustrates a cross sectional view of an embodiment of a wounddressing;

FIG. 4C illustrates another exploded view of an embodiment of a wounddressing;

FIG. 4D illustrates a cross sectional view of the wound dressingembodiment of FIG. 4C;

FIG. 5A illustrates an embodiment of a wound dressing trimmable at abridge portion;

FIG. 5B illustrates another embodiment of a wound dressing trimmable ata bridge portion;

FIG. 6 illustrates an embodiment of a trimmable wound dressingcomprising a plurality of portions or cells;

FIG. 7 illustrates an embodiment of a trimmable T-shaped wound dressingcomprising a plurality of portions with multiple port attachment sites;

FIG. 8 illustrates an embodiment of a trimmable wound dressing withmultiple port attachment sites;

FIGS. 9A and 9B illustrate one embodiment of spacer layer material;

FIGS. 10A-10D illustrate one embodiment of acquisition distributionlayer material;

FIGS. 11A and 11B illustrate one embodiment of absorbent layer material;

FIGS. 12A and 12B illustrate one embodiment of obscuring layer material;

FIG. 13 illustrates one embodiment of an adhesive spread on cover layermaterial;

FIGS. 14A-14D illustrate one embodiment of a sealing strip assemblywhich may be used with a dressing and/or fluidic connector;

FIGS. 15A-15L illustrate differential pressure results of dry testingvarious materials for bridge sections of a dressing;

FIGS. 16A-16J illustrate differential pressure results of wet testingvarious materials for bridge sections of a dressing;

FIGS. 17A-17B illustrate one embodiment of a trimmable dressing having areduced height bridging portion;

FIG. 18 illustrates an embodiment of a heel dressing;

FIG. 19 illustrates an embodiment of an extremity dressing;

FIGS. 20A and 20B illustrate two embodiments of a trimmable dressinghaving a skirt portion;

FIG. 21 illustrates an embodiment of a trimmable wound dressingcomprising a plurality of portions or cells;

FIGS. 22A through 22E illustrate another embodiment of acquisitiondistribution layer material; and

FIGS. 23A through 23E illustrate another embodiment of acquisitiondistribution layer material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

I. Introduction

Embodiments disclosed herein relate to apparatuses and methods oftreating a wound with reduced pressure, including pump and wounddressing components and apparatuses. The apparatuses and componentscomprising the wound overlay and packing materials, if any, aresometimes collectively referred to herein as dressings.

It will be appreciated that throughout this specification reference ismade to a wound. It is to be understood that the term wound is to bebroadly construed and encompasses open and closed wounds in which skinis torn, cut or punctured or where trauma causes a contusion, or anyother superficial or other conditions or imperfections on the skin of apatient or otherwise that benefit from reduced pressure treatment. Awound is thus broadly defined as any damaged region of tissue wherefluid may or may not be produced. Examples of such wounds include, butare not limited to, abdominal wounds or other large or incisionalwounds, either as a result of surgery, trauma, sterniotomies,fasciotomies, or other conditions, dehisced wounds, acute wounds,chronic wounds, subacute and dehisced wounds, traumatic wounds, flapsand skin grafts, lacerations, abrasions, contusions, burns, diabeticulcers, pressure ulcers, stoma, surgical wounds, cosmetic wounds, traumaand venous ulcers or the like. Wounds may include readily accessible anddifficult to access wounds, exposed and concealed wounds, large andsmall wounds, regular and irregular shaped wounds, planar andtopographically irregular, uneven or complex wounds, more preferably ona site selected from the torso, limb and extremities such as heel,sacrum, axial, inguinal, shoulder, neck, leg, foot, digit, knee, axilla,arm and forearm, elbow, hand or for sealing a crevice adjacent oradjoining a wound site, selected from such as sacral cleft, fossar andthe like.

It will be understood that embodiments of the present disclosure aregenerally applicable to use in topical negative pressure (“TNP”) therapysystems. TNP therapy has sometimes been referred to as vacuum assistedclosure V.A.C. or negative pressure wound therapy (NPWT), and isapplicable to a broad range of wounds such as chronic wounds, incisionalwounds, open wounds and abdominal wounds or the like. Briefly, negativepressure wound therapy assists in the closure and healing of many formsof “hard to heal” wounds by reducing tissue oedema; encouraging bloodflow and granular tissue formation; removing excess exudate and mayreduce bacterial load (and thus infection risk). In addition, thetherapy allows for less disturbance of a wound leading to more rapidhealing. TNP therapy systems may also assist on the healing ofsurgically closed wounds by removing fluid and by helping to stabilizethe tissue in the apposed position of closure. A further beneficial useof TNP therapy can be found in grafts and flaps where removal of excessfluid is important and close proximity of the graft to tissue isrequired in order to ensure tissue viability. During TNP therapy, asuction source such as a vacuum pump or the like is utilized to create anegative pressure region—that is to say, a region where an experiencedpressure is below that of the surroundings. The suction source creates anegative pressure via a dressing or drape positioned over and sealedabout or around the periphery of the wound. Wound exudate and otherpotentially harmful material is enclosed under the dressing or drape andextracted therefrom.

As is used herein, reduced or negative pressure levels, such as −X mmHg,represent pressure levels that are below standard atmospheric pressure,which corresponds to 760 mmHg (or 1 atm, 29.93 in HG, 101.325 kPa,14.696 psi, etc.). Accordingly, a negative pressure value of −X mmHgreflects absolute pressure that is X mmHg below 760 mmHg or, in otherwords, an absolute pressure of (760−X) mmHg. In addition, negativepressure that is “less”, “smaller” or “<” than −X mmHg corresponds topressure that is closer to atmospheric pressure (e.g., −40 mmHg is lessthan −60 mmHg). Negative pressure that is “more”, “greater” or “>” than−X mmHg corresponds to pressure that is further from atmosphericpressure (e.g., −80 mmHg is more than −60 mmHg). However, set pointpressures may be referred to as positive in charts in the figures forpurposes of generating chart data in a conventional format.

The negative pressure range for some embodiments of the presentdisclosure can be approximately −80 mmHg, or between about −20 mmHg and−200 mmHg. Note that these pressures are relative to normal ambientatmospheric pressure. Thus, −200 mmHg would be about 560 mmHg inpractical terms. In some embodiments, the pressure range can be betweenabout −40 mmHg and −150 mmHg. Alternatively a pressure range of up to−75 mmHg, up to −80 mmHg or over −80 mmHg can be used. Also in otherembodiments a pressure range of below −75 mmHg can be used.Alternatively, a pressure range of over approximately −100 mmHg, or even−150 mmHg, can be supplied by the negative pressure apparatus. In someembodiments of wound closure devices described here, increased woundcontraction can lead to increased tissue expansion in the surroundingwound tissue. This effect may be increased by varying the force appliedto the tissue, for example by varying the negative pressure applied tothe wound over time, possibly in conjunction with increased tensileforces applied to the wound via embodiments of the wound closuredevices. In some embodiments, negative pressure may be varied over timefor example using a sinusoidal wave, square wave, and/or insynchronization with one or more patient physiological indices (e.g.,heartbeat). Canisterless NPWT (omitting a dedicated canister to containwound exudate) has also been considered using negative pressure valuesin the same range as conventional NPWT, more preferably −40 to −200mmHg, and more preferably −40 to −140 mmHg.

II. Overview of Example Systems

FIG. 1 illustrates an embodiment of a TNP wound treatment system 100comprising a wound dressing 110 in combination with a pump 150. Asstated above, the wound dressing 110 can be any wound dressingembodiment disclosed herein including without limitation dressingembodiment or have any combination of features of any number of wounddressing embodiments disclosed herein. Here, the dressing 110 may beplaced over a wound as described previously, and a conduit 130 may thenbe connected to the port 120, although in some embodiments the dressing101 may be provided with at least a portion of the conduit 130preattached to the port 120. Preferably, the dressing 110 is provided asa single article with all wound dressing elements (including the port120) pre-attached and integrated into a single unit. The wound dressing110 may then be connected, via the conduit 130, to a source of negativepressure such as the pump 150. The pump 150 can be miniaturized andportable, although larger conventional pumps may also be used with thedressing 110. In some embodiments, the pump 150 may be attached ormounted onto or adjacent the dressing 110. A connector 140 may also beprovided so as to permit the conduit 130 leading to the wound dressing110 to be disconnected from the pump, which may be useful for exampleduring dressing changes.

FIGS. 2A-2D illustrate the use of an embodiment of a TNP wound treatmentsystem being used to treat a wound site on a patient. FIG. 2A shows awound site 200 being cleaned and prepared for treatment. Here, thehealthy skin surrounding the wound site 200 is preferably cleaned andexcess hair removed or shaved. The wound site 200 may also be irrigatedwith sterile saline solution if necessary. Optionally, a skin protectantmay be applied to the skin surrounding the wound site 200. If necessary,a wound packing material, such as foam or gauze, may be placed in thewound site 200. This may be preferable if the wound site 200 is a deeperwound.

After the skin surrounding the wound site 200 is dry, and with referencenow to FIG. 2B, the wound dressing 110 may be positioned and placed overthe wound site 200. Preferably, the wound dressing 110 is placed withthe wound contact layer 2102 over and/or in contact with the wound site200. In some embodiments, an adhesive layer is provided on the lowersurface 2101 of the wound contact layer 2102, which may in some cases beprotected by an optional release layer to be removed prior to placementof the wound dressing 110 over the wound site 200. Preferably, thedressing 110 is positioned such that the port 2150 is in a raisedposition with respect to the remainder of the dressing 110 so as toavoid fluid pooling around the port. In some embodiments, the dressing110 is positioned so that the port 2150 is not directly overlying thewound, and is level with or at a higher point than the wound. To helpensure adequate sealing for TNP, the edges of the dressing 110 arepreferably smoothed over to avoid creases or folds.

With reference now to FIG. 2C, the dressing 110 is connected to the pump150. The pump 150 is configured to apply negative pressure to the woundsite via the dressing 110, and typically through a conduit. In someembodiments, and as described above in FIG. 1 , a connector may be usedto join the conduit from the dressing 110 to the pump 150. Upon theapplication of negative pressure with the pump 150, the dressing 110may, in some embodiments, partially collapse and present a wrinkledappearance as a result of the evacuation of some or all of the airunderneath the dressing 110. In some embodiments, the pump 150 may beconfigured to detect if any leaks are present in the dressing 110, suchas at the interface between the dressing 110 and the skin surroundingthe wound site 200. Should a leak be found, such leak is preferablyremedied prior to continuing treatment.

Turning to FIG. 2D, additional fixation strips 210 may also be attachedaround the edges of the dressing 110. Such fixation strips 210 may beadvantageous in some situations so as to provide additional sealingagainst the skin of the patient surrounding the wound site 200. Forexample, the fixation strips 210 may provide additional sealing for whena patient is more mobile. In some cases, the fixation strips 210 may beused prior to activation of the pump 150, particularly if the dressing110 is placed over a difficult to reach or contoured area.

Treatment of the wound site 200 preferably continues until the wound hasreached a desired level of healing. In some embodiments, it may bedesirable to replace the dressing 110 after a certain time period haselapsed, or if the dressing is full of wound fluids. During suchchanges, the pump 150 may be kept, with just the dressing 110 beingchanged.

III. Overview of Example Layers

FIGS. 3A-3C illustrate cross-sections through a wound dressing 2100similar to the wound dressing of FIG. 1 according to an embodiment ofthe disclosure. A view from above the wound dressing 2100 is illustratedin FIG. 1 with the line A-A indicating the location of the cross-sectionshown in FIGS. 3A and 3B. The wound dressing 2100, which canalternatively be any wound dressing embodiment disclosed hereinincluding without limitation wound dressing 110 or any combination offeatures of any number of wound dressing embodiments disclosed herein,can be located over a wound site to be treated. The dressing 2100 may beplaced to as to form a sealed cavity over the wound site. In a preferredembodiment, the dressing 2100 comprises a backing layer 2140 attached toa wound contact layer 2102, both of which are described in greaterdetail below. These two layers 2140, 2102 are preferably joined orsealed together so as to define an interior space or chamber. Thisinterior space or chamber may comprise additional structures that may beadapted to distribute or transmit negative pressure, store wound exudateand other fluids removed from the wound, and other functions which willbe explained in greater detail below. Examples of such structures,described below, include a transmission layer 2105 and an absorbentlayer 2110.

As illustrated in FIGS. 3A-3C, a lower surface 2101 of the wounddressing 2100 may be provided with an optional wound contact layer 2102.The wound contact layer 2102 can be a polyurethane layer or polyethylenelayer or other flexible layer which is perforated, for example via a hotpin process, laser ablation process, ultrasound process or in some otherway or otherwise made permeable to liquid and gas. The wound contactlayer 2102 has a lower surface 2101 and an upper surface 2103. Theperforations 2104 preferably comprise through holes in the wound contactlayer 2102 which enable fluid to flow through the layer 2102. The woundcontact layer 2102 helps prevent tissue ingrowth into the other materialof the wound dressing. Preferably, the perforations are small enough tomeet this requirement while still allowing fluid to flow therethrough.For example, perforations formed as slits or holes having a size rangingfrom 0.025 mm to 1.2 mm are considered small enough to help preventtissue ingrowth into the wound dressing while allowing wound exudate toflow into the dressing. In some configurations, the wound contact layer2102 may help maintain the integrity of the entire dressing 2100 whilealso creating an air tight seal around the absorbent pad in order tomaintain negative pressure at the wound.

Some embodiments of the wound contact layer 2102 may also act as acarrier for an optional lower and upper adhesive layer (not shown). Forexample, a lower pressure sensitive adhesive may be provided on thelower surface 2101 of the wound dressing 2100 whilst an upper pressuresensitive adhesive layer may be provided on the upper surface 2103 ofthe wound contact layer. The pressure sensitive adhesive, which may be asilicone, hot melt, hydrocolloid or acrylic based adhesive or other suchadhesives, may be formed on both sides or optionally on a selected oneor none of the sides of the wound contact layer. When a lower pressuresensitive adhesive layer is utilized may be helpful to adhere the wounddressing 2100 to the skin around a wound site. In some embodiments, thewound contact layer may comprise perforated polyurethane film. The lowersurface of the film may be provided with a silicone pressure sensitiveadhesive and the upper surface may be provided with an acrylic pressuresensitive adhesive, which may help the dressing maintain its integrity.In some embodiments, a polyurethane film layer may be provided with anadhesive layer on both its upper surface and lower surface, and allthree layers may be perforated together.

A layer 2105 of porous material can be located above the wound contactlayer 2102. This porous layer, or transmission layer, 2105 allowstransmission of fluid including liquid and gas away from a wound siteinto upper layers of the wound dressing. In particular, the transmissionlayer 2105 preferably ensures that an open air channel can be maintainedto communicate negative pressure over the wound area even when theabsorbent layer has absorbed substantial amounts of exudates. The layer2105 should preferably remain open under the typical pressures that willbe applied during negative pressure wound therapy as described above, sothat the whole wound site sees an equalized negative pressure. The layer2105 may be formed of a material having a three dimensional structure.For example, a knitted or woven spacer fabric (for example Baltex 7970weft knitted polyester) or a non-woven fabric could be used.

A layer 2110 of absorbent material is provided above the transmissionlayer 2105. The absorbent material, which comprise a foam or non-wovennatural or synthetic material, and which may optionally comprise asuper-absorbent material, forms a reservoir for fluid, particularlyliquid, removed from the wound site. In some embodiments, the layer 2100may also aid in drawing fluids towards the backing layer 2140.

With reference to FIGS. 3A-3C, a masking or obscuring layer 2107 can bepositioned beneath at least a portion of the backing layer 2140. In someembodiments, the obscuring layer 2107 can have any of the same features,materials, or other details of any of the other embodiments of theobscuring layers disclosed herein, including but not limited to havingany viewing windows or holes. Additionally, the obscuring layer 2107 canbe positioned adjacent to the backing layer, or can be positionedadjacent to any other dressing layer desired. In some embodiments, theobscuring layer 2107 can be adhered to or integrally formed with thebacking layer. Preferably, the obscuring layer 2107 is configured tohave approximately the same size and shape as the absorbent layer 2110so as to overlay it. As such, in these embodiments the obscuring layer2107 will be of a smaller area than the backing layer 2140.

The material of the absorbent layer 2110 may also prevent liquidcollected in the wound dressing 2100 from flowing freely within thedressing, and preferably acts so as to contain any liquid collectedwithin the absorbent layer 2110. The absorbent layer 2110 also helpsdistribute fluid throughout the layer via a wicking action so that fluidis drawn from the wound site and stored throughout the absorbent layer.This helps prevent agglomeration in areas of the absorbent layer. Thecapacity of the absorbent material must be sufficient to manage theexudates flow rate of a wound when negative pressure is applied. Sincein use the absorbent layer experiences negative pressures the materialof the absorbent layer is chosen to absorb liquid under suchcircumstances. A number of materials exist that are able to absorbliquid when under negative pressure, for example superabsorber material.The absorbent layer 2110 may typically be manufactured from ALLEVYN™foam, Freudenberg 114-224-4 and/or Chem-Posite™11C-450. In someembodiments, the absorbent layer 2110 may comprise a compositecomprising superabsorbent powder, fibrous material such as cellulose,and bonding fibers. In a preferred embodiment, the composite is anairlaid, thermally-bonded composite.

An orifice 2145 is preferably provided in the backing layer 2140 toallow a negative pressure to be applied to the dressing 2100. A suctionport 2150 is preferably attached or sealed to the top of the backinglayer 2140 over an orifice 2145 made into the dressing 2100, andcommunicates negative pressure through the orifice 2145. A length oftubing 2220 may be coupled at a first end to the suction port 2150 andat a second end to a pump unit (not shown) to allow fluids to be pumpedout of the dressing. The port may be adhered and sealed to the backinglayer 2140 using an adhesive such as an acrylic, cyanoacrylate, epoxy,UV curable or hot melt adhesive. The port 2150 is formed from a softpolymer, for example a polyethylene, a polyvinyl chloride, a silicone orpolyurethane having a hardness of 30 to 90 on the Shore A scale. In someembodiments, the port 2150 may be made from a soft or conformablematerial.

Preferably the absorbent layer 2110 and the obscuring layer 2107 includeat least one through hole 2146 located so as to underlie the port 2150.The through hole 2146, while illustrated here as being larger than thehole through the obscuring layer 2107 and backing layer 2140, may insome embodiments be bigger or smaller than either. Of course, therespective holes through these various layers 2107, 2140, and 2110 maybe of different sizes with respect to each other. As illustrated inFIGS. 3A-3C a single through hole can be used to produce an openingunderlying the port 2150. It will be appreciated that multiple openingscould alternatively be utilized. Additionally should more than one portbe utilized according to certain embodiments of the present disclosureone or multiple openings may be made in the absorbent layer and theobscuring layer in registration with each respective port. Although notessential to certain embodiments of the present disclosure the use ofthrough holes in the super-absorbent layer may provide a fluid flowpathway which remains unblocked in particular when the absorbent layer2100 is near saturation.

The aperture or through-hole 2146 is preferably provided in theabsorbent layer 2110 and the obscuring layer 2107 beneath the orifice2145 such that the orifice is connected directly to the transmissionlayer 2105. This allows the negative pressure applied to the port 2150to be communicated to the transmission layer 2105 without passingthrough the absorbent layer 2110. This ensures that the negativepressure applied to the wound site is not inhibited by the absorbentlayer as it absorbs wound exudates. In other embodiments, no aperturemay be provided in the absorbent layer 2110 and/or the obscuring layer2107, or alternatively a plurality of apertures underlying the orifice2145 may be provided.

The backing layer 2140 is preferably gas impermeable, but moisture vaporpermeable, and can extend across the width of the wound dressing 2100.The backing layer 2140, which may for example be a polyurethane film(for example, Elastollan SP9109) or hydrocolloid film, having a pressuresensitive adhesive on one side, is impermeable to gas and this layerthus operates to cover the wound and to seal a wound cavity over whichthe wound dressing is placed. In this way an effective chamber is madebetween the backing layer 2140 and a wound site where a negativepressure can be established. The backing layer 2140 is preferably sealedto the wound contact layer 2102 in a border region 2200 around thecircumference of the dressing, ensuring that no air is drawn in throughthe border area, for example via adhesive or welding techniques. Thebacking layer 2140 protects the wound from external bacterialcontamination (bacterial barrier) and allows liquid from wound exudatesto be transferred through the layer and evaporated from the film outersurface. The backing layer 2140 preferably comprises two layers; apolyurethane or hydrocolloid film and an adhesive pattern spread ontothe film. The film is preferably moisture vapor permeable and may bemanufactured from a material that has an increased water transmissionrate when wet.

The absorbent layer 2110 may be of a greater area than the transmissionlayer 2105, such that the absorbent layer overlaps the edges of thetransmission layer 2105, thereby ensuring that the transmission layerdoes not contact the backing layer 2140. This provides an outer channel2115 of the absorbent layer 2110 that is in direct contact with thewound contact layer 2102, which aids more rapid absorption of exudatesto the absorbent layer. Furthermore, this outer channel 2115 ensuresthat no liquid is able to pool around the circumference of the woundcavity, which may otherwise seep through the seal around the perimeterof the dressing leading to the formation of leaks.

As shown in FIG. 3A, one embodiment of the wound dressing 2100 comprisesan aperture 2146 in the absorbent layer 2110 situated underneath theport 2150. In use, for example when negative pressure is applied to thedressing 2100, a wound facing portion of the port 150 may thus come intocontact with the transmission layer 2105, which can thus aid intransmitting negative pressure to the wound site even when the absorbentlayer 2110 is filled with wound fluids. Some embodiments may have thebacking layer 2140 be at least partly adhered to the transmission layer2105. In some embodiments, the aperture 2146 is at least 1-2 mm largerthan the diameter of the wound facing portion of the port 2150, or theorifice 2145.

A filter element 2130 that is impermeable to liquids, but permeable togases is provided to act as a liquid barrier, and to ensure that noliquids are able to escape from the wound dressing. The filter elementmay also function as a bacterial barrier. Typically the pore size is 0.2μm. Suitable materials for the filter material of the filter element2130 include 0.2 micron Gore™ expanded PTFE from the MMT range, PALLVersapore™ 200R, and Donaldson™ TX6628. Larger pore sizes can also beused but these may require a secondary filter layer to ensure fullbioburden containment. As wound fluid contains lipids it is preferable,though not essential, to use an oleophobic filter membrane for example1.0 micron MMT-332 prior to 0.2 micron MMT-323. This prevents the lipidsfrom blocking the hydrophobic filter. The filter element can be attachedor sealed to the port and/or the backing layer 2140 over the orifice2145. For example, the filter element 2130 may be molded into the port2150, or may be adhered to both the top of the backing layer 2140 andbottom of the port 2150 using an adhesive such as, but not limited to, aUV cured adhesive.

In FIG. 3B, an embodiment of the wound dressing 2100 is illustratedwhich comprises spacer elements 2152, 2153 in conjunction with the port2150 and the filter 2130. With the addition of such spacer elements2152, 2153, the port 2150 and filter 2130 may be supported out of directcontact with the absorbent layer 2110 and/or the transmission layer2105. The absorbent layer 2110 may also act as an additional spacerelement to keep the filter 2130 from contacting the transmission layer2105. Accordingly, with such a configuration contact of the filter 2130with the transmission layer 2105 and wound fluids during use may thus beminimized. As contrasted with the embodiment illustrated in FIG. 3A, theaperture 2146 through the absorbent layer 2110 and the obscuring layer2107 may not necessarily need to be as large or larger than the port2150, and would thus only need to be large enough such that an air pathcan be maintained from the port to the transmission layer 2105 when theabsorbent layer 2110 is saturated with wound fluids.

With reference now to FIG. 3C, which shares many of the elementsillustrated in FIGS. 3A-3B, the embodiment illustrated here comprisesthe backing layer 2140, masking layer 2107, and absorbent layer 2110,all of which have a cut or opening made therethrough which communicatedirectly to the transmission layer 2105 so as to form the orifice 2145.The suction port 2150 is preferably situated above it and communicateswith the orifice 2145.

In particular for embodiments with a single port 2150 and through hole,it may be preferable for the port 2150 and through hole to be located inan off-center position as illustrated in FIGS. 3A-3C and in FIG. 1 .Such a location may permit the dressing 2100 to be positioned onto apatient such that the port 2150 is raised in relation to the remainderof the dressing 2100. So positioned, the port 2150 and the filter 2130may be less likely to come into contact with wound fluids that couldprematurely occlude the filter 2130 so as to impair the transmission ofnegative pressure to the wound site.

FIG. 4A illustrates an exploded view of a dressing 3400 for use innegative pressure wound therapy, wherein the various layers areillustrated in an exploded view. Although this figure illustrates adressing having one particular shape, the construction of the layers canbe applied to any of the embodiments identified below, including FIG.5A—FIG. 8 , and any of the dressing shapes and configurations describedin the patent applications incorporated by reference herein. Thedressing 3400 comprises a release layer 3480, wound contact layer 3460,a spacer or transmission layer 3450, an acquisition distribution layer3440 (which may also be considered a transmission layer) and which mayoptionally have an orifice located so as to underlie the suction portand align with the orifices in 3410 (labelled 3411), 3420 and 3430, anabsorbent layer 3430, an obscuring layer 3420, and a backing layer 3410.The dressing 3400 may be connected to a port. At least the wound contactlayer 3460, spacer layer 3450, absorbent layer 3430, obscuring layer3420, and backing layer 3410 may have properties as described withrespect to particular embodiments above, such as the embodiments ofFIGS. 3A-3C, as well as or instead of the properties described below.

The dressing 3400 may comprise a wound contact layer 3460 for sealingthe dressing 3400 to the healthy skin of a patient surrounding a woundarea. Certain embodiments of the wound contact layer may comprise threelayers: a polyurethane film layer, a lower adhesive layer and an upperadhesive layer. The upper adhesive layer may assist in maintaining theintegrity of the dressing 3400, and the lower adhesive layer may beemployed for sealing the dressing 3400 to the healthy skin of a patientaround a wound site. As described above, in some embodiments withrespect to FIGS. 3A-3C, some embodiments of the polyurethane film layermay be perforated. Some embodiments of the polyurethane film layer andupper and lower adhesive layers may be perforated together after theadhesive layers have been applied to the polyurethane film. In someembodiments a pressure sensitive adhesive, which may be a silicone, hotmelt, hydrocolloid or acrylic based adhesive or other such adhesives,may be formed on both sides or optionally on a selected one side of thewound contact layer. In certain embodiments, the upper adhesive layermay comprise an acrylic pressure sensitive adhesive, and the loweradhesive layer may comprise a silicone pressure sensitive adhesive. Inother embodiments the wound contact layer 3460 may not be provided withadhesive. In some embodiments, the wound contact layer 3460 may betransparent or translucent. The film layer of the wound contact layer3460 may define a perimeter with a rectangular or a square shape. Arelease layer 3480 may be removably attached to the underside of thewound contact layer 3460, for example covering the lower adhesive layer,and may be peeled off using flaps 3481. Some embodiments of the releaselayer 3480 may have a plurality of flaps extending along the length ofthe layer 3480.

Some embodiments of the dressing 3400 may comprise a spacer layer 3450,which is one type of transmission layer that may be provided forcommunicating fluid through the dressing 3400. The spacer layer 3450 maycomprise a porous material or 3D fabric configured to allow for thepassage of fluids therethrough away from the wound site and into theupper layers of the dressing 3400. In particular, the spacer layer 3450can ensure that an open air channel can be maintained to communicatenegative pressure over the wound area even when the absorbent layer 3430has absorbed substantial amounts of exudates. The spacer layer 3450should remain open under the typical pressures that will be appliedduring negative pressure wound therapy as described above, so that thewhole wound site sees an equalized negative pressure.

Some embodiments of the spacer layer 3450 may be formed of a materialhaving a three dimensional structure. For example, a knitted or wovenspacer fabric (for example Baltex 7970 weft knitted polyester) or anon-woven fabric can be used. In some embodiments, the spacer layer 3450can have a 3D polyester spacer fabric layer. This layer can have a toplayer which is a 84/144 textured polyester, and a bottom layer which canbe a 100 denier flat polyester and a third layer formed sandwichedbetween these two layers which is a region defined by a knittedpolyester viscose, cellulose or the like monofilament fiber. In use,this differential between filament counts in the spaced apart layerstends to draw liquid away from the wound bed and into a central regionof the dressing 3400 where the absorbent layer 3430 helps lock theliquid away or itself wicks the liquid onwards towards the cover layer3410 where it can be transpired. Other materials can be utilized, andexamples of such materials are described in U.S. Patent Pub. No.2011/0282309, which are hereby incorporated by reference and made partof this disclosure. However, the spacer layer 3450 may be optional, andfor example may be optional in embodiments of the dressing 3400 whichcomprise the acquisition distribution layer 3440, described below.

Some embodiments may comprise a wicking or acquisition distributionlayer (ADL) 3440. The ADL is another type of transmission layer that maybe provided for communicating fluid through the dressing 3400. The ADLmay be configured to horizontally wick fluid such as wound exudate as itis absorbed upward through the layers of the dressing 3400. Lateralwicking of fluid may allow maximum distribution of the fluid through theabsorbent layer 3430 and may enable the absorbent layer 3430 to reachits full holding capacity. This may advantageously increase moisturevapor permeation and efficient delivery of negative pressure to thewound site. Some embodiments of the ADL 3440 may comprise viscose,polyester, polypropylene, polyethylene, cellulose (for examplepolysaccharide or repeated disaccharide), or a combination of some orall of these, and the material may be needle-punched. Some embodimentsof the ADL 3440 may comprise polyethylene in the range of 40-150 gramsper square meter (gsm). Some embodiments of the ADL may comprise a heavyfibrous melt material. Some embodiments of the ADL may be relativelyporous to allow for the passage of fluids, including gas, therethrough.One example of an ADL may comprise a lightweight, felt-like, viscosematerial, which may be 80 gsm (or approximately 80 gsm). Someembodiments of the ADL may comprise cellulose in the range of 40-160 gsm(or about 40 to about 160 gsm), for example 80 (or about 80) gsm. TheADL may be constructed from a material which resists compression underthe levels of negative pressure commonly applied during negativepressure therapy.

The dressing 3400 may further comprise an absorbent or superabsorbentlayer 3430. The absorbent layer can be manufactured from ALLEVYN™ foam,Freudenberg 114-224-4 and/or Chem-Posite™11C-450, cellulose-basedairlaid, or any other suitable material. In some embodiments, theabsorbent layer 3430 can be a layer of non-woven cellulose fibers havingsuper-absorbent material in the form of dry particles dispersedthroughout. Use of the cellulose fibers introduces fast wicking elementswhich help quickly and evenly distribute liquid taken up by thedressing. The juxtaposition of multiple strand-like fibers leads tostrong capillary action in the fibrous pad which helps distributeliquid.

For example, some embodiments of the absorbent layer 3430 may comprise alayered construction of an upper layer of non-woven cellulose fibers,superabsorbent particles (SAP), and a lower layer of cellulose fiberswith 40-80% SAP. In some embodiments, the absorbent layer 3430 may be anair-laid material. Heat fusible fibers can optionally be used to assistin holding the structure of the pad together. Some embodiments maycombine cellulose fibers and air-laid materials, and may furthercomprise up to 60% SAP. Some embodiments may comprise 60% SAP and 40%cellulose. Other embodiments of the absorbent layer may comprise between60% and 90% (or between about 60% and about 90%) cellulose matrix andbetween 10% and 40% (or between about 10% and about 40%) superabsorbentparticles. For example, the absorbent layer may have about 20%superabsorbent material and about 80% cellulose fibers. It will beappreciated that rather than using super-absorbing particles or inaddition to such use, super-absorbing fibers can be utilized accordingto some embodiments of the present invention. An example of a suitablematerial is the Product Chem-Posite™ 11 C-450 available from EmergingTechnologies Inc (ETi) in the USA.

Super-absorber particles/fibers can be, for example, sodium polyacrylateor carbomethoxycellulose materials or the like or any material capableof absorbing many times its own weight in liquid. In some embodiments,the material can absorb more than five times its own weight of 0.9% W/Wsaline, etc. In some embodiments, the material can absorb more than 15times its own weight of 0.9% W/W saline, etc. In some embodiments, thematerial is capable of absorbing more than 20 times its own weight of0.9% W/W saline, etc. Preferably, the material is capable of absorbingmore than 30 times its own weight of 0.9% W/W saline, etc. The absorbentlayer 3430 can have one or more through holes 3431 located so as tounderlie the suction port.

Some embodiments of the present disclosure may optionally employ amasking or obscuring layer 3420 to help reduce the unsightly appearanceof a dressing 3400 during use due to the absorption of wound exudate.The obscuring layer 3420 may be a colored portion of the absorbentmaterial, or may be a separate layer that covers the absorbent material.The obscuring layer 3420 may be one of a variety of colors such as blue,orange, yellow, green, or any color suitable for masking the presence ofwound exudate in the dressing 3400. For example, a blue obscuring layer3420 may be a shade of blue similar to the shade of blue commonly usedfor the material of medical gowns, scrubs, and drapes. Some embodimentsof the obscuring layer 3420 may comprise polypropylene spunbondmaterial. Further, some embodiments of the obscuring layer 3420 maycomprise a hydrophobic additive or coating. Other embodiments maycomprise a thin fibrous sheet of 60, 70, or 80 gsm.

The obscuring layer may comprise at least one viewing window 3422configured to allow a visual determination of the saturation level ofthe absorbent layer. The at least one viewing window 3422 may compriseat least one aperture made through the obscuring layer. The at least oneviewing window 3422 may comprise at least one uncolored region of theobscuring layer. Some embodiments of the obscuring layer may comprise aplurality of viewing windows or an array of viewing windows.

The masking capabilities of the obscuring layer 3420 should preferablyonly be partial, to allow clinicians to access the information theyrequire by observing the spread of exudate across the dressing surface.A obscuring layer 3420 may be partial due to material propertiesallowing wound exudate to slightly alter the appearance of the dressingor due to the presence of at least one viewing window 3422 in acompletely obscuring material. The partial masking nature of theobscuring layer 3420 enables a skilled clinician to perceive a differentcolour caused by exudate, blood, by-products etc. in the dressingallowing for a visual assessment and monitoring of the extent of spreadacross the dressing. However, since the change in colour of the dressingfrom its clean state to a state with exudate contained is only a slightchange, the patient is unlikely to notice any aesthetic difference.Reducing or eliminating a visual indicator of wound exudate from apatient is likely to have a positive effect on their health, reducingstress for example.

The obscuring layer 3420 can have one or more through holes located soas to underlie the suction port. Some embodiments may have a maltesecross 3421 or other shaped cutout underlying the suction port, whereinthe diameter of the maltese cross 3421 is greater than the diameter ofthe port. This may allow a clinician to easily asses the amount of woundexudate absorbed into the layers beneath the port.

The dressing 3400 may also comprise a backing layer, or cover layer 3410extending across the width of the wound dressing. The cover layer 3410may be gas impermeable but moisture vapor permeable. Some embodimentsmay employ a polyurethane film (for example, Elastollan SP9109) or anyother suitable material. For example, certain embodiments may comprisetranslucent or transparent 30 gsm EU33 film (from Smith & NephewExtruded Films). The cover layer 3410 may have a pressure sensitiveadhesive on the lower side, thereby creating a substantially sealedenclosure over the wound in which negative pressure may be established.The cover layer can protect the wound as a bacterial barrier fromexternal contamination, and may allow liquid from wound exudates to betransferred through the layer and evaporated from the film outersurface.

The cover layer 3410 can have an orifice 3411 located so as to underliethe suction port. The orifice 3411 may allow transmission of negativepressure through the cover layer 3410 to the wound enclosure. The portmay be adhered and sealed to the cover film using an adhesive such as anacrylic, cyanoacrylate, epoxy, UV curable or hot melt adhesive. Someembodiments may have a plurality of orifices for the attachment ofmultiple ports or other sources of negative pressure or other mechanismsfor distributing fluid.

FIG. 4B illustrates a cross sectional view of the wound dressing 3400,displaying an embodiment of the relative thicknesses of layers of thedressing 3400. In some embodiments, the wound contact layer 3460 may beflat and the top film layer 3410 may be contoured over the inner layersof the dressing 3400. The spacer layer 3450 may be half as thick as theacquisition distribution layer 3440 in some embodiments. In someembodiments, the absorbent layer 3430 may be about 1.5 times thickerthan the spacer layer 3450. The obscuring layer 3420 may be about halfthe thickness of the spacer layer 3450.

FIG. 4C illustrates another embodiment of a wound dressing 3900, withthe various layers illustrated in an exploded view. Although this figureillustrates a dressing having one particular shape, the construction ofthe layers can be applied to any of the embodiments identified below,including FIG. 5A-FIG. 8 , and any of the dressing shapes andconfigurations described in the patent applications incorporated byreference herein. The wound dressing may comprise a release layer 3980,wound contact layer 3960, a transmission layer 3950, an acquisitiondistribution layer 3940, an adhesive layer 3970, an absorbent layer3930, an obscuring layer 3920, and a backing layer 3910. At least thewound contact layer 3960, transmission layer 3950, absorbent layer 3930,obscuring layer 3920, and backing layer 3910 may have properties asdescribed with respect to particular embodiments above, such as theembodiments of FIGS. 3A-3C, as well as or instead of the propertiesdescribed below.

The dressing 3900 may be connected to a port 3990, as illustrated inFIG. 4D (shown without the release layer 3980). At least the backinglayer 3910, obscuring layer 3920, absorbent layer 3930, and acquisitiondistribution layer 3940 may have openings underlying the port 3990, andthe port 3990 may comprise a three-dimensional fabric 3997 and a filterelement 3995 overlying the openings. In some embodiments, the opening3921 in the obscuring layer may be cross-shaped. As illustrated, thecross-shaped opening 3921 may comprise four arms of roughly equal lengthextending outward from a central point of intersection of the arms,wherein the sides of each arm are angled or arced such that the far endof each arm is wider than the end closest to the intersection. The farends of the four arms may comprise arcs, for example four arcs from asingle circle, giving the cross a rounded shape. The opening 3911 in thebacking layer 3910, opening 3931 in the absorbent layer 3930, andopening 3941 in the acquisition distribution layer 3940 may be alignedwith the central intersection point of the cross-shaped opening 3921.The openings 3911, 3931, and 3941 may be the same size or of varyingsizes.

The backing layer 3910 (as well as the backing layer of previouslydescribed embodiments) may comprise, in some embodiments, EU33 film andmay optionally have a pressure-sensitive adhesive provided on a lowersurface thereof. For example, the adhesive may be a water dispersibleacrylic adhesive, for example K5. The adhesive may be able to be patternspread, and may be hydrophilic.

The obscuring layer 3920 may be provided to increase patient comfort bymasking the presence of wound exudate absorbed by the inner layers ofthe dressing. The obscuring layer 3920 may have an outer perimeter thatis spaced 1 mm, or approximately 1 mm, or 0.5 mm to 3 mm, orapproximately 0.5 to approximately 3 mm, beyond the adjacent perimeteredge of the dressing layer or layers provided beneath it, for examplethe absorbent layer 3930, ADL 3940, and/or transmission layer 3950. Theobscuring layer 3920 may be provided with a plurality of viewing windows3922 which may be used to assess the spread of exudate across thedressing 3900. The cross-shaped opening 3921 may be used as a viewingwindow to ascertain the level of saturation of the layer or layersunderlying an attached port. The width of the cross-shaped opening 3921may be greater than the width of an attached port to enable suchassessment. Some embodiments of the obscuring layer 3920 (includingother embodiments of the obscuring layer previously described) maycomprise polypropylene spunbond material of suitable colors such asdescribed above, including medical blue. Further, some embodiments ofthe obscuring layer 3920 may comprise a hydrophobic additive or coating.

The absorbent layer 3930 may be configured to absorb and retain exudatefrom a patient's wound. The absorbent layer 3930 will preferably beconstructed from a material which has good absorbent qualities undernegative pressure. In some embodiments (including any of the earlierdescribed embodiments), the absorbent layer may comprise cellulosefibers or air-laid materials. Some embodiments may comprise a cellulosefibers with 40-80% superabsorbent particles (SAP), for example 40%-60%(or about 40% to about 60%) SAP or 60%-80% (or about 60% to about 80%)SAP. Heat fusible fibers can optionally be used to assist in holding thestructure of the absorbent pad together. Some embodiments may combinecellulose fibers and air-laid materials, for example as a hybrid bondedairlaid composite in the range of 400-500 gsm (or about 400 to about 500gsm), for example 460 (or about 460) gsm. The absorbent layer 3930 mayinclude polyacrylate superabsorber powder to increase the absorbentcapabilities of the material. Some embodiments of the absorbent layer3930 comprise a tissue dispersant layer. This may, in some embodiments,be provided along the lower surface of the layer, resulting in anasymmetric construction of the absorbent layer. The tissue dispersantlayer may comprise a heat fusible binder to aid in holding the layerstructure together. The tissue dispersant layer may provide theadvantage of enabling fluid transport. In some embodiments, the tissuedispersant layer may comprise a hot melt adhesive such as ethylene vinylacetate (EVA), for example applied as a solution to cellulose fibers ofthe absorbent layer.

The adhesive layer 3970 may bond an upper surface of the acquisitiondistribution layer 3940 to a lower surface of the absorbent layer 3930.As illustrated, in some embodiments the adhesive layer 3970 may comprisean adhesive web or net, for example a fusible web such as Wonder-Web®.In other embodiments, the adhesive layer 3970 may comprise adhesivetape, for instance strips or mesh of double sided adhesive film. In yetother embodiments the acquisition distribution layer 3940 and theabsorbent layer 3930 may be heat laminated. Some embodiments may employa hot melt adhesive, such as ethylene vinyl acetate (EVA). For example,EVA hot melt adhesive powder may be sprinkled over the ADL 3940, whichmay then be heat bonded (heat laminated) to the absorbent layer 3930. Insome embodiments the acquisition distribution layer 3940 and theabsorbent layer 3930 may be stitched or sewn together, and the adhesivelayer 3970 may comprise suitable fibers, strands, or threads. In someembodiments of a trimmable dressing 3900, other layers may be bondedtogether in a similar manner to provide consistency with respect tolayer alignment when the dressing is cut on one or more sides, such thatthe layers remain together when the sides of the dressing are cut, andsuch that there is not vertical separation of the layers at the cutportions. Preferred embodiments of the adhesive layer 3970 arehydrophilic so as not to affect the transport of water and/orwater-based solutions between the acquisition distribution layer 3940and absorbent layer 3930. In some embodiments, the adhesive layer maycomprise a fine sprinkle of adhesive powder such that the acquisitiondistribution layer 3940 and absorbent layer 3930 are not bonded togetheracross the entire upper and lower surfaces, respectively, but may bemerely tacked together in a number of locations. However, someembodiments of the dressing may be constructed without the use of anadhesive between the acquisition distribution layer 3940 and absorbentlayer 3930.

The acquisition distribution layer (ADL) 3940 may be constructed so asto advantageously horizontally wick fluid, such as wound exudate, as itis absorbed upward through the layers of the dressing 3900. Such lateralwicking of fluid may allow maximum distribution of the fluid through theabsorbent layer 3930, enabling the absorbent layer 3930 to reach itsfull holding capacity. Some embodiments of the ADL 3940 (including anyembodiments of the ADL previously described) may comprise cellulose inthe range of 40-160 gsm (or about 40 to about 160 gsm), for example 80(or about 80) gsm. The ADL may be constructed from a material whichresists compression under the levels of negative pressure commonlyapplied during negative pressure therapy. The acquisition distributionlayer (ADL) 3940 may be constructed so as to advantageously verticallywick fluid, such as wound exudate. Facilitating rapid movement of woundexudate from the transmission layer to the absorbent layer is desirable.Additionally judicious choice of material can reduce re-wetting ofliquid from the absorbent layers down into lower layers, this phenomenonis known as “back wetting” or “re-wetting”. Suitable materials that showan enhancement of this effect include Slimcore TL4 (150 gsm) fromLibeltex BVBA or equivalent.

Some embodiments of the acquisition distribution layer (ADL) 3940 mayinclude several internal layers. For example, one material suitable foruse as an ADL includes a lower wicking or acquisition layer comprisingsubstantially vertically extending fibers for vertical wicking of fluidand further includes an upper distribution layer comprisingsubstantially horizontally extending fibers for horizontal wicking offluid. Some ADL materials can include three or more layers, for examplea lower wicking layer and two upper distribution layers. Otherconfigurations can have one or more distribution layers positionedbetween upper and lower acquisition layers.

Some embodiments of the dressing 3900 may optionally comprise a spaceror transmission layer 3950. The transmission layer 3950 may comprise aporous material or 3D fabric configured to allow for the passage offluids therethrough away from the wound site and into the upper layersof the dressing 3900. In particular, the transmission layer 3950 shouldremain open under the typical pressures that will be applied duringnegative pressure wound therapy as described above, so that the wholewound site sees an equalized negative pressure. In some embodiments, theacquisition distribution layer 3940 may be sufficient to maintain eventransmission of negative pressure throughout the dressing 3900 and thetransmission layer 3950 may be excluded. An outer perimeter of thetransmission layer may be spaced 5 mm, or approximately 5 mm, or 2 mm to8 mm, or approximately 2 mm to approximately 8 mm, inward of theadjacent perimeter edge of the dressing layer positioned above thetransmission layer, for example the ADL 3940 or absorbent layer 3930.

The dressing 3900 may optionally comprise a wound contact layer 3960 forsealing the dressing 3900 to the healthy skin of a patient surrounding awound area. As discussed above with respect to FIG. 4A, the woundcontact layer 3960 may comprise flexible polyurethane film, and may beprovided with a silicone adhesive on a lower surface thereof. The woundcontact layer 3960 may be perforated to allow for the transmission offluids such as wound exudate therethrough, so that the fluids may bepassed through or retained by the inner layers of the dressing 3900.Prior to use, the wound contact layer 3960 may be protected by aprotective release layer 3980, which may be provided with at least oneset of flaps 3981 for removing or peeling off the release layer 3980.

IV. Overview of Example Dressing and Bridge Configurations

FIGS. 5A and 5B illustrate various embodiments of a wound dressing 500which may be trimmable at a bridge portion 530. As used herein, a bridgeor bridging or skirt portion can refer to a section of a dressing thatbridges transmission of negative pressure across at least a portion ofthe dressing. Such bridge or bridging or skirt portions may, in someembodiments, bridge two segments of absorbent pad portions, however inother embodiments only one absorbent pad portion may connect to a bridgeportion. Bridge portions can also function to bridge negative pressuretransmission to other bridge portions.

The dressing 500 may comprise a backing layer 510, an absorbent layerand/or one or more transmission layers formed in a main portion 520 andat least one additional portion 540 separated by a gap 560 and connectedby a bridge portion 530, and a port 550. In some embodiments, the mainportion 520, additional portion 540 and bridge portion 530 comprise oneor more transmission layers such as described above between an optionalwound contact layer and a backing layer 510. The transmission layer(s)may comprise any material configured to transmit fluid and/or negativepressure. For example some embodiments of the transmission layer(s) maycomprise the spacer layer 3450 of FIG. 4A, discussed above, which may beconfigured to evenly distribute negative pressure and vertically wickfluids. Other embodiments of the transmission layer(s) may comprise theacquisition distribution layer 3440 of FIG. 4A, discussed above, whichmay be configured to horizontally or laterally wick fluid. Otherembodiments of the spacer layer and acquisition distribution layer arediscussed with respect to FIGS. 4C and 9A, 9B, and 10A-10B discussedbelow. Further embodiments of the transmission layer can include anopen-cell reticulated foam, as discussed below with respect to Table 1and FIGS. 15A-16J. Some embodiments of the transmission layer(s) maycomprise a first layer configured to vertically wick fluid and a secondlayer, positioned above the first layer, configured to horizontally wickfluid. One or both of the first and second layer may be present in themain portion 520, additional portion 540 and bridge portions 530. Insome embodiments, the same layers may be found throughout the mainportion 520, additional portion 540 and bridge portions 530.

In some embodiments, the portions of dressing 500 may have differentlayered structures. For example, in some embodiments the bridge portions530 can comprise a material not included in the main portion 520 oradditional portion 540, for example open-cell reticulated foam. In otherembodiments a transmission layer may extend across the bridge portions530, main portion 520, and additional portion 540, and the main portion520, and additional portion 540 can additionally include an absorbentlayer.

In any or all of the main portion 520, additional portion 540, andbridge portion 530, the dressing 500 may further comprise an optionalabsorbent material such as described herein positioned between thebacking layer 510 and the one or more transmission layers. In someembodiments, the absorbent layer may have a similar footprint to the oneor more transmission layers. In other embodiments, the absorbent layermay be located at main portion 520 and at least one additional portion540, but the absorbent layer may not be included in the bridge portion530. As illustrated, the dressing has an elongate, rectangular shape,though other shapes are also contemplated. The absorbent layerpreferably has a smaller footprint than the backing layer, so that theabsorbent layer is completely surrounded by the backing layer. It willbe appreciated that in some embodiments, the absorbent layer is anintegral, one-piece layer of material that extends across the mainportion 520, the additional portion 540 and in the bridge portion 530 oralternatively extends across the main portion 520 but not the additionalportion 540 or the bridge portion 530. Some embodiments may bemanufactured without the port 550 and may include at least one area forattaching a port. For example, the port 550 may simply be an opening inthe backing layer for attaching a separate port member.

The dressing 500 may also comprise other layers as discussed above withrespect to FIGS. 3A-4B. For instance, the dressing 500 may comprise awound contact layer which may be sealed to the backing layer 510,thereby creating an enclosed chamber for the absorbent layer and/or oneor more transmission layers and any other layers within the dressing.The wound contact layer and backing layer may be sealed along aperimeter with a certain distance from the edge of the sealed perimeterto the edge of the absorbent layer. The wound contact layer and backinglayer may also be sealed together throughout some or all of the area ofa gap 560 between portions of the inner layers.

The transmission layers, as described above, may be provided for thetransmission of negative pressure throughout the dressing and fordrawing wound exudate away from the wound site and into the upper layersof the dressing 500 and/or laterally spreading wound exudate across thearea of the dressing 500. As described above, the transmission layer(s)may comprise one or both of the spacer layer and acquisitiondistribution layer described with respect to FIG. 4A. Use of one or moreof these layers may advantageously maintain fluid transmission throughnarrow portions of the dressing such as the bridge portions, and maykeep these narrow portions from partially or completely collapsing undernegative pressure. Further, having material such as the acquisitiondistribution material and/or absorbent material sized to overlap theedge of the transmission layer(s) may beneficially mitigate discomfortor pressure on skin during wear of the dressing.

Further, use of one or both of the spacer layer and acquisitiondistribution layer as the transmission layer(s) in the bridge portion530 may provide advantages for internally sealing a trimmed portion ofthe dressing 500. Some embodiments of the spacer and acquisitiondistribution layers may have open, fibrous structures. After a dressingis trimmed or cut, in order to reseal the dressing, an adhesive such ascuring silicone may be injected into the exposed portion of thetransmission layer(s), thus creating a plug that substantially seals theexposed edge internally. Absorbent material may not be present in thebridge portion 530, as some embodiments of the absorbent material may betoo dense to allow adhesive to flow into the layer and thus does notallow for an exposed edge to be sealed internally. However, inembodiments containing a dense absorbent material in the bridge portion530, an exposed end may be still be sealed externally, such as bycovering the entire exposed edge with silicone from backing layer toskin or sealing the exposed edge with adhesive tape or a sealing strip.Having absorbent material and/or acquisition distribution material inthe bridge portion 530 may provide the benefit of distributing absorbedliquid between the main portion 520 and any additional portions 540.

As illustrated in FIG. 5B, the absorbent layer and/or one or moretransmission layers may comprise a main portion 520 and a plurality ofadditional portions 540. The additional portions may be smaller than orthe same size as the main portion 550. For example, as measured alongthe longitudinal length of a rectangular dressing, the length of theadditional portions may be smaller than the length of the main portion,and each additional portion may have the same length. As illustrated,the main portion 520 is connected to the first additional portion 540 byone bridge portion 530 aligned along the center longitudinal axis of thedressing 500, and each additional portion is connected to the nextadditional portion by a similar bridge. The bridge portion may in FIGS.5A and 5B may also be located off the center axis, for example at theside of the dressing. Other embodiments may employ a plurality ofbridges for connecting the portions of the dressing. For example, oneembodiment may employ two bridges to connect adjacent portions, whereinthe bridges are located at the side edges of the adjacent portions nextto the sealed perimeter. Another embodiment may employ two bridges eachlocated a distance away from the side edges of the adjacent portions.

In some embodiments the main portion 520 may be a precalculated minimumlength, and some or all of the additional portions 540 may have lengthsthat can be removed for custom sizing of the dressing to a variety oflengths exceeding the minimum length. The main portion length may belonger than the additional portion lengths, or the main portion may havethe same length as the additional portions. Such embodiments may beadvantageous for a long incision such as a leg incision made for a veinharvest. In an embodiment, the main portion 520 may be a minimumincision length or minimum leg length, and the additional portions 540may be included in the dressing to achieve a length up to a maximumincision length or a maximum leg length. In use, the dressing may betrimmed according to the incision or leg length of the patient acrossthe bridge portions, for example at cut line 570 described below. Insome embodiments, additional ports or port attachment sites may belocated on some or all of the additional portions in order to maintain asubstantially even level of negative pressure throughout a relativelylong dressing.

The bridge portion 530 in FIGS. 5A and 5B creates a continuous path fornegative pressure delivery between multiple portions of the dressing.The bridge portion 530 may have a width that is less than ⅛, ¼, or ⅓ thewidth of adjacent portions of absorbent material and/or one or moretransmission layers. A wider bridge portion allows for greatertransmission of negative pressure and fluids such as wound exudate,however a narrower bridge portion is advantageous for sealing a dressingtrimmed at the bridge portion. Further, patient comfort may be enhancedif the bridge portion 530 is wide enough to cover a wound or anincision. Embodiments of the dressings described herein may balancethese factors according to a variety of purposes and/or considerations,and therefore the width of bridge portion 530 may vary. In someembodiments the bridge portion 530 may be approximately 15 mm wide,however other embodiments may be 10 mm to 20 mm (or about 10 mm to about20 mm) wide or thinner or thicker. For example, a spacer material usedas a transmission layer in a bridge portion can have a width ofapproximately 1 mm and a height of approximately 2 mm and maintainclinically appropriate negative pressure transmission. Accordingly, insome embodiments, the cross-sectional area of a bridge portion may be 2mm² or approximately 2 mm², or more. Other materials may have varyingminimum widths and heights for use in bridge portions according to theirnegative pressure transmission properties. The bridges can have any ofthe ranges of dimensions from the examples discussed below with respectto FIGS. 15A-16J. In embodiments employing a plurality of bridgeportions, the bridge portions may all be a uniform width or may havevarying widths. In some embodiments, the bridge portion 530 may comprisea wound contact layer, one or more transmission layers (which may be oneor both of the wicking layer or acquisition distribution layersdescribed above with respect to FIG. 4A), and a backing layer. Someembodiments of the bridge portion 530 may further comprise an absorbentor superabsorbent layer. The layers in the bridge portions 530 may becontinuous with layers found in the portions 520 or 540 of the dressing,or they may be discrete layers positioned side-by-side. In someembodiments, the bridge portions 530, main portion 520, and additionalportions 540 may be a continuous layer of a single material, for exampleopen-cell reticulated foam, positioned between a wound contact layer anda top film layer.

In a dressing applied to a nonplanar surface, the bridge portions mayalso advantageously provide enhanced flexing of the dressing forconforming to the nonplanar surface. Further, the bridge portions mayenhance side flexing capabilities of the dressing for covering a curvedor arcuate incision. In some embodiments, the location and width of thebridge portions may be selected for both connecting a plurality oftrimmable portions as well as for flexibility of the dressing.

The dressing 500 may be trimmed at or across the bridge portion 530.Although the dressing may be trimmed at any portion, trimming thedressing at bridge portion 530, for example perpendicular to the lengthof the dressing, enables easier sealing as a narrower cross sectionalarea is exposed, and thus less area requires sealing after trimming. Insome embodiments, the gap 560 may have the same width as the distancefrom the sealed perimeter edge to the absorbent layer, such that whenthe dressing is trimmed along a trim line 570 adjacent to the additionalportion 540 the sealed perimeter around the inner layer(s) issubstantially unchanged. In some embodiments this width may beapproximately 2.5 cm, and in other embodiments may be any width suitablefor maintaining the seal between the backing layer and the wound contactlayer. It will be appreciated that the dressing may be trimmed atlocations other than the illustrated trim line 570, which is includedfor illustrative purposes only, for example at a trim line in the centerof the bridge portion 530 or at a diagonal or curved trim line.

In some embodiments, the absorbent layer and/or other layers of thewound dressing may be prescored for sizing. Other layers, such as thetransmission layer(s) or acquisition distribution layer, may also beprescored. The backing layer may not be scored, as a through hole maylimit the ability of the backing layer to function as a bacterialbarrier or compromise the ability of the dressing to maintain negativepressure. Other embodiments may include a printed or indented pattern onsome or all of the layers to indicate possible trim lines.

Each of the main portion 520 and additional portion(s) 540 may beconsidered a negative pressure treatment module, all or some of whichmay be used to provide negative pressure to a wound site. For example,if the dressing 500 of FIG. 5A or 5B is left untrimmed, all of themodules cooperate together to provide negative pressure to a wound site.Alternatively, if one or more of the additional portions 540 is trimmedand removed, the remaining portion(s) or module(s) can be used toprovide negative pressure to the wound site. After trimming, thedressing 500 may be sealed by an adhesive strip, a piece of a sealingdrape, by another dressing, or by a sealant. In some embodiments, aretention strip may be applied at the interface of the dressing edge andthe skin. The retention strips may be applied to cover trimmed dressingborders. In some embodiments the retention strips may comprise apressure-sensitive adhesive on the lower surface, and in otherembodiments may be applied over a sealant. It will be appreciated thatany other adhesive method or mechanism may be used to seal the dressing.For example, a sealant may be applied with a tool such as a syringearound the trimmed area in order to reseal the chamber of the dressingor to seal the dressing to a patient. Some embodiments of the dressingmay be self-sealing.

FIG. 6 illustrates an embodiment of a trimmable wound dressing 600comprising a plurality of portions or cells 620. As illustrated, thecells 620 are repeating to form a plurality of repeating negativepressure treatment modules. The dressing 600 may comprise a sealedperimeter 610 of a backing layer and a wound contact layer, a pluralityof cells 620, a plurality of bridges 630 connecting adjacent portions,and a port member 640. As described above, the dressing 600 may betrimmed at the bridge portions and sealed along the trim line. Each ofthe cells 620 may include absorbent material and/or one or moretransmission layers as described above, along with other optionallayers. The bridge portions 630 may comprise a wound contact layer, oneor more transmission layers (which may be one or both of the wickinglayer or acquisition distribution layers described above with respect toFIG. 4A), and a backing layer. Some embodiments of the bridge portions630 may further comprise an absorbent or superabsorbent layer. Thelayers in the bridge portions 630 may be continuous with layers found inthe cells 620, or they may be discrete layers positioned side-by-side.The cells 620 and bridge portions 630 can be formed from a continuoussingle layer in some embodiments, for example open-cell reticulatedfoam.

As illustrated, the dressing comprises a 4×4 array of cells 620. Otherembodiments may comprise any suitable array of cells, or may beconfigured as a long rolled dressing N cells wide. The cells may beconnected by one or more narrow bridge portions 630 and separated bygaps 650. The backing layer and wound contact layer may be sealedtogether throughout the gaps. By trimming at the bridge portions 630,the integrity of the dressing may be maintained even as the dressing issignificantly resized. For example, the dressing may be trimmed so thatonly one inner cell or a group of inner cells remain, and the layers ofthe dressing will not separate due to the sealing of the backing layerand wound contact layer throughout the area of the gaps 650.

In some embodiments, the center cells of the dressing 600 may beremoved. This may provide benefits, for example, when the dressing isused to cover a grafted skin flap or sutured skin flap. The dressing maybe resized so that the unsutured skin is substantially uncovered by thedressing. Thus, the removed sections would otherwise cover the healthyskin of the flap. Covering the healthy skin with the dressingpotentially creates problem such as exposing the wound to bacteria onthe surface of the flap and exposing the healthy skin of the flap toexcess moisture. The dressing may also be resized accordingly to covercircular, curved, or otherwise irregularly shaped suture lines.

The port member 640 may be located, as illustrated, on a corner cell ofthe dressing 600. However, in other embodiments the port may be locatedon a different cell. Some embodiments may employ multiple ports, eachport connected to a different cell. For example, a large dressing orlonged rolled dressing may comprise a port at an edge cell of every Nrows, such every as four rows or five rows. Some embodiments may,instead of the illustrated port member 640, comprise a port attachmentsite or sites.

FIG. 7 illustrates an embodiment of a trimmable wound dressing 700comprising a plurality of portions with multiple port attachment sites760. Similar to the dressing 600 described above, the T-shaped dressing700 comprises a backing layer and wound contact layer having a sealedperimeter 710 around a plurality of cells 720 containing absorbentmaterial and/or one or more transmissions layer connected by bridgeportions 730 and separated by gaps 740. The bridge portions 730 maycomprise a wound contact layer, one or more transmission layers (whichmay be one or both of the wicking layer or acquisition distributionlayers described above with respect to FIG. 4A), and a backing layer.Some embodiments of the bridge portions 730 may further comprise anabsorbent or superabsorbent layer. The layers in the bridge portions 730may be continuous with layers found in the cells 720, or they may bediscrete layers positioned side-by-side. The backing layer and woundcontact layer may also be sealed together throughout some or all of thearea of the gaps 740. As described above, the dressing 700 may betrimmed at the bridge portions and sealed along the trim line. Althoughthe dressing is illustrated as being T-shaped, this is for illustrativepurposes only, and the dressing may be a variety of branched shapes.Each branch may comprise one or more cells connected by one or morebridge portions. The cells 720 and bridge portions 730 can be formedfrom a continuous single layer in some embodiments, for exampleopen-cell reticulated foam.

The dressing comprises a plurality of port attachment sites 760. Eachattachment site 760 may be a hole in the backing layer and may becovered with a removable tab 760. The tab may comprise a suitablebacking material with a layer of adhesive on some or all of the lowersurface. Some embodiments may comprise a ring of adhesive sized tosurround the hole 750 in the backing layer. The tab 760 may be removedso that a port may be attached to the backing layer over the hole 750for transmission of negative pressure into the dressing 700. In someembodiments, port attachments may be secured at just one port attachmentsite. In other embodiments, port attachments may be secured over aplurality of attachment sites as needed for transmission of negativepressure throughout the dressing. Some ports may comprise an adhesive onthe lower surface thereof for attachment to the dressing. Someembodiments of the dressing may comprise an adhesive layer for attachingthe port.

FIG. 8 illustrates an embodiment of a trimmable wound dressing 800 withmultiple port attachment sites 840. The dressing comprises a backinglayer and wound contact layer having a sealed perimeter 810, anabsorbent layer 820, a spacer layer 830 below the absorbent layer, and aplurality of holes 840 in the backing layer covered by tabs 850. Thespacer layer 830 may be one or both of the transmission layer andacquisition distribution layer discussed above. It will be appreciatedthat in some embodiments, only one of the absorbent layer or spacerlayer may be provided, with the other layer being optional.

The dressing 800 is configured as a roll with port attachment sites 840spaced a distance apart along the upper surface. Trimmable portions maybe located between adjacent port attachment sites 840 where the dressing800 may be cut or separated. Accordingly, the dressing 800 may beconsidered to include a plurality of repeating negative pressuretreatment modules, where one or more of the modules can be removed andthe removed module(s) can subsequently be used to provide negativepressure to the wound site. In some embodiments this distance may beuniform between all port attachment sites, and in other embodiments thedistance may vary. The dressing roll may be custom sized by unrolling alength of dressing, trimming the dressing, sealing the two sides, andattaching a port or ports to one or more port attachment sites. In someembodiments, unused port attachment sites 840 may remain sealed byadhesive tabs 850. In some embodiments, the spacer layer 830, andoptionally the absorbent layer 820, may comprise a bridge portion orplurality of bridge portions located between each port attachment sitefor ease of sealing a trimmed dressing. It will be appreciated that anyof the dressings described above may be configured as a trimmable rollwith a plurality of port attachment sites located a distance apart onthe roll. For example, an elongate dressing configured as a roll mayinclude narrower bridging portions spaced along a length of the dressingbetween port attachment sites to facilitate trimming of the dressing toa suitable size.

In some embodiments, a wound contact layer 860 can be positioned underthe spacer layer 830. At least a portion of lower surface of woundcontact layer 860 may be provided with an adhesive for sealing to apatient's healthy skin. Prior to use, the adhesive can be covered with aprotective layer (not illustrated). Similar to the multi-part protectivelayer employing folded handles, as illustrated in FIGS. 14C and 14D anddiscussed in more detail below, the protective layer over the loweradhesive of dressing 800 can have a central portion and two outer handleportions. The handle portions can run lengthwise, for example along ornear the sealed perimeter 810, so that the handles will be available foreasy removal of the protective layer on any cut portion of the dressing800.

Such adaptable, resizable dressings may provide the advantage ofreducing the inventory of dressings that a hospital or clinic isrequired to keep. Rather than maintaining a large inventory of dressingsconsisting of a multitude of shapes and sizes for all possible wound orincision sites, a hospital or clinic may only require one or several ofthe dressings described herein which can be modified to suit any patientneeds. Further, it may be advantageous from a manufacturing perspectiveto produce adaptable dressings.

V. Overview of Example Layer Materials

FIGS. 9A and 9B illustrate one embodiment of spacer layer, ortransmission layer, material which may be used in any of the dressingembodiments described above, and which may also be used in any of theport or fluidic connector embodiments described above. The spacer ortransmission material is preferably formed of a material having a threedimensional structure, and may have a top layer and a bottom layercomprising a knit pattern. For example, a knitted or woven spacer fabric(for example Baltex 7970 weft knitted polyester) or a non-woven fabriccould be used. The top and bottom fabric layers may comprise polyester,such as 84/144 textured polyester or a flat denier polyester. Othermaterials and other linear mass densities of fiber could of course beused. In some embodiments, the top and bottom fabric layers may be thesame pattern and the same material, and in other embodiments they may bedifferent patterns and/or different materials. The top fabric layer mayhave more filaments in a yarn used to form it than the number offilaments making up the yarn used to form the bottom fabric layer, inorder to control moisture flow across the transmission layer.Particularly, by having a filament count greater in the top layer, thatis to say, the top layer is made from a yarn having more filaments thanthe yarn used in the bottom layer, liquid tends to be wicked along thetop layer more than the bottom layer. FIG. 9A illustrates one possibleknit pattern for a top or bottom fabric layer.

As illustrated in the side view of FIG. 9B, between the top and bottomfabric layers may be a plurality of filaments. The filaments maycomprise a monofilament fiber or a multistrand fiber, and may be knittedpolyester viscose or cellulose. In some embodiments, a majority of thefilaments, by volume, may extend vertically (that is, perpendicular tothe plane of the top and bottom layers), or substantially or generallyvertically. In another embodiment, 80%-90% (or approximately 80% toapproximately 90%) of the filaments or more, by volume, may extendvertically, or substantially or generally vertically. In anotherembodiment, all or substantially all of the filaments, by volume, mayextend vertically, or substantially or generally vertically. In someembodiments, a majority, 80%-90% (or approximately 80% to approximately90%) of the filaments or more, or even all or substantially all of thefilaments, extend upward from the bottom fabric layer and/or downwardfrom the top fabric layer, and in some embodiments, such filamentsextend over a length more than half the distance between the top andbottom fabric layers. In some embodiments, a majority, 80%-90% (orapproximately 80% to approximately 90%) of the filaments or more, oreven all or substantially all of the filaments, span a distance that isgreater in a direction perpendicular to the top and bottom fabric layers(a vertical direction) than in a direction parallel to the top andbottom fabric layers (a horizontal direction). The orientation of suchfilaments may promote vertical wicking of fluid through the spacerlayer. In some embodiments, the ratio of the amount of fluid wickedvertically through the spacer material to the amount of fluid wickedlaterally across the spacer material when under negative pressure may be2:1 or more, or approximately 2:1 or more, or may be up to 10:1 or more,or approximately 10:1 or more, in some embodiments. Such filaments mayalso keep the top and bottom layers spaced apart when exposed tocompressive forces or negative pressure. Some embodiments of the spacerlayer may have a tensile strength that substantially prevents tearing bytypical force applied by human hands, and accordingly would need to besevered by other means, such as being cut or sliced, if implemented in atrimmable dressing.

FIGS. 10A-10D illustrate one embodiment of acquisition distributionlayer (ADL) material which may be used in any of the dressingembodiments described above, and which may also be used in any of theport or fluidic connector embodiments described above. To those versedin the art of acquisition distribution layers it would be obvious thatother ADL materials may be used to achieve a similar effect. Such ADLlayers may be composed of multiple fibre types and be complex instructure and design. The ADL material, in an uncompressed state, may be0.1 mm to 4 mm thick, or approximately 0.1 mm to approximately 4 mmthick, and in some embodiments may be 1.2 mm thick, or approximately 1.2mm thick, in an uncompressed state. The ADL material may comprise aplurality of loosely packed fibers, which may be arranged in asubstantially horizontal fibrous network.

In some embodiments, the ADL material may consist of a mix of two fibertypes. One may be a flat fiber which may be 20 μm to 50 μm in width, orapproximately 20 μm to approximately 50 μm in width, and may comprise acellulosic based material. The other fiber may be a two component fiberthat has an inner core that is 8 μm to 10 μm in diameter, orapproximately is 8 μm to approximately 10 μm in diameter, and an outerlayer with a thickness of 1 μm to 2 μm, or approximately 1 μm toapproximately 2 μm. The two component fiber may be a mix of apolyethylene (PE) type material, and polyethylene terephthalate (PET).In some embodiments the inner core of the two component fiber may be PETand the outer layer may be PE. The PE/PET fibers may have a smoothsurface morphology, while the cellulosic fibers may have a relativelyrougher surface morphology. In some embodiments the ADL material maycomprise about 60% to about 90% cellulosic fibers, for exampleapproximately 75% cellulosic fibers, and may comprise about 10% to about40% PE/PET fibers, for example approximately 25% PE/PET fibers.

FIG. 10A illustrates a backscatter scanning electron microscope (SEM)plan view of a sample portion of acquisition distribution layer materialat 140× magnification. FIG. 10B illustrates an SEM cross sectional viewat 250× magnification. As illustrated in FIG. 10B, a majority of thefiber volume may extend horizontally (that is, parallel to the plane ofthe top and bottom surfaces of the material), or substantially orgenerally horizontally. In another embodiment, 80%-90% (or approximately80% to approximately 90%) or more of the fiber volume may extendhorizontally, or substantially or generally horizontally. In anotherembodiment, all or substantially all of the fiber volume may extendhorizontally, or substantially or generally horizontally. In someembodiments, a majority, 80%-90% (or approximately 80% to approximately90%) of the fibers or more, or even all or substantially all of thefibers, span a distance perpendicular to the thickness of the ADLmaterial (a horizontal or lateral distance) that is greater than thethickness of the ADL material. In some embodiments, the horizontal orlateral distance spanned by such fibers is 2 times (or about 2 times) ormore, 3 times (or about 3 times) or more, 4 times (or about 4 times) ormore, 5 times (or about 5 times) or more, or 10 times (or about 10times) or more the thickness of the ADL material. The orientation ofsuch fibers may promote lateral wicking of fluid through the ADLmaterial. This may more evenly distribute fluid such as wound exudatethroughout the ADL material. In some embodiments, the ratio of theamount of fluid wicked laterally across the ADL material to the amountof fluid wicked vertically through the ADL material under negativepressure may be 2:1 or more, or approximately 2:1 or more, or may be upto 10:1 or more, or approximately 10:1 or more, in some embodiments.

FIG. 10C is a two dimensional microtomographic cross sectional view of acompressed portion of a sample of ADL material which is approximately9.2 mm long. FIG. 10D is an SEM cross sectional view at 130×magnification of the compressed portion illustrated in FIG. 10C. Suchcompressed portions may occur in the ADL material may occur due to theapplication of pressure to the material. FIGS. 10C and 10D furtherillustrate the horizontal network of ADL fibers.

FIGS. 11A and 11B illustrate one embodiment of absorbent material whichmay be used in any of the dressing embodiments described above. FIG. 11Aillustrates a three dimensional microtomographic cross sectional view ofa sample of absorbent material, depicting a fibrous compositioninterspersed with superabsorbent particles. The absorbent material may,for example, be any of the materials described in U.S. Patent Pub. No.2012/308780, titled “Absorbent Structure,” filed May 25, 2012, thecontents of which are hereby incorporated by reference in theirentirety.

FIG. 11B is a cross sectional schematic diagram of an embodiment of theabsorbent material illustrating a plurality of layers within theabsorbent material. The absorbent material may have a textured layer4210 on one side of a fibrous network, the fibrous network defining thebulk of the absorbent material and comprising layers 4220, 4240, and4250. Superabsorbent particles 4230 may be dispersed throughout layers4220, 4240, and 4250. The textured layer 4210, also referred to as the“tissue dispersant layer” in above portions of this specification, maybe configured to laterally transmit fluid. Though depicted as thelowermost layer of the absorbent material, the textured layer 4210 mayin some embodiments be positioned as the uppermost layer of theabsorbent material, and in some embodiments may be positioned as boththe lowermost and uppermost layers of the absorbent material. Thetextured layer 4210 may comprise flat fibers 20 μm to 50 μm in width, orapproximately 20 μm to approximately 50 μm in width. The textured layer4210 may comprise 1 to 2 or approximately 1 to approximately 2 layers ofthe flat fibers, and the textured layer 4210 may have an overallthickness of 0.04 mm, or approximately 0.04 mm.

The bulk of the absorbent material, comprising layers 4220, 4240, and4250, may have a thickness of 1.7 mm, or approximately 1.7 mm, or mayhave a thickness in the range of 0.5 mm to 5.0 mm, or about 0.5 mm toabout 5.0 mm. The bulk of the absorbent material may comprise a mix oftwo fiber types arranged in a fibrous network, for example thecellulosic fiber having a width of 20 μm to 50 μm, or approximately 20μm to approximately 50 μm, and the PE/PET composite fiber, describedabove with respect to the ADL material. The superabsorbent particles4230 may be irregularly shaped and varied in size, and may have adiameter of up to 1 mm, or approximately 1 mm. The superabsorbentparticles 4230 may comprise a sodium acrylate type material. There maybe relatively fewer superabsorbent particles in a portion of theuppermost surface of the bulk of the absorbent material (the surface oflayer 4250 opposite the textured layer 4210), for example in anuppermost surface having a thickness of approximately 0.1 mm.

Layer 4220 may be a liquid absorption layer configured to draw liquidupward through the material towards layers 4240 and 4250. Layer 4240 maybe a storage layer configured to hold absorbed liquid. Layer 4220 may bea liquid distribution layer configured to apply a “reverse suction”effect to the liquid storage layer 4240 in order to inhibit (orsubstantially inhibit) absorbed liquid from leaking back down throughthe lower layers of the absorbent material, a phenomenon which iscommonly known as “back wetting.”

Superabsorbent particles 4230 may be distributed primarily within thestorage layer, may extend partially into the absorption layer 4220 andliquid distribution layer 4250, or may be distributed evenly (orsubstantially evenly) throughout the layers. The layers 4220, 4240, and4250 may overlap with a portion of adjacent layers, and may or may notbe separable.

FIGS. 12A and 12B illustrate one embodiment of obscuring layer materialwhich may be used in any of the dressing embodiments described above.FIG. 12A illustrates a photographic plan view of obscuring material,depicting a material comprising a fibrous network having a reoccurringregularly spaced criss-cross diamond pattern. The diamond shaped patternmay, in one embodiment, be 1.2 mm long by 1.0 mm wide, and may have athickness of approximately 0.04 mm thick, consisting of fibers that aremore densely packed relative to the surrounding area of the material.The diamond shaped pattern may increase structural stability of thefibrous network of the material, for example serving as “tacking”points. FIG. 12B illustrates a three dimensional microtomographicperspective view of the compressed diamond pattern and the surroundinguncompressed fibers.

Some embodiments of the obscuring material may comprise polypropylenespunbond material. Further, some embodiments of the obscuring materialmay comprise a hydrophobic additive or coating, for example ahydrophobic wash designed to permeate the fibers of the obscuringmaterial to make the material substantially waterproof while permittingvapor permeability. Other embodiments may comprise a thin fibrous sheetof 60, 70, or 80 gsm. The fibers of the obscuring material may, in oneembodiment, comprise layers of polypropylene (PP) fibers having a smoothsurface morphology, and the PP fibers may have a thickness ofapproximately 25 μm. In some embodiments, the obscuring material mayhave a thickness of 0.045 mm or about 0.045 mm, or may have a thicknessin the range of 0.02 mm to 0.5 mm, or about 0.02 mm to about 0.5 mm.

FIG. 13 illustrates one embodiment of an adhesive spread onapproximately one square centimeter of a film material, which may beused as the cover or backing layer in any of the dressing embodiments orfluidic connector embodiments described above. The adhesive on the filmhas been covered with carbon powder for ease of illustrating the spreadof the adhesive. The adhesive may comprise, for example, an acrylatetype adhesive, for example K5 adhesive, and may be laid down in a crisscross pattern. In some embodiments, the adhesive material may coverapproximately 45.5%±approximately 1.3% of the film surface. The patternand coverage of the adhesive may vary so long as the configuration issuitable for desired vapor permeability.

VI. Overview of Example Sealing Strips

FIGS. 14A-14D illustrate one embodiment of a sealing strip assembly 4501which may be used with a wound dressing and/or fluidic connector toprovide additional sealing against the skin of the patient surroundingthe wound dressing or fluidic connector. Sealing strips may also be usedto reseal a cut or punctured wound dressing or fluidic connector. Thesealing strips of FIGS. 14A-14D may be used, for example, like thefixation strips 210 of FIG. 2D.

As illustrated in FIG. 14A (top view), a plurality of sealing strips4501 (labeled 4501 a-4501 f) may be provided together on one sheet 4500with a plurality of perforations or weakened lines 4515, separating theindividual sealing strips on the sheet. In some embodiments anywherefrom 2 to 10 or more sealing strips may be provided on one sheet. Asillustrated, six sealing strips 4501 a, 4501 b, 4501 c, 4501 d, 4501 eand 4501 f are provided on one sheet 4500 in FIG. 14A. In otherembodiments each sealing strip may be provided separately, or aplurality of separate sealing strips may be provided, for example in akit. A kit may be provided in the form of a tray, for example a sealedtray, which may include one or more sheets containing a plurality ofsealing strips 4501 separated by the plurality of perforations orweakened lines 4515, or other embodiments of sealing strips asdescribed. The kit may also contain a wound dressing with a fluidicconnector that may be pre-connected to the wound dressing or separatelyprovided. The wound dressing may have any of the shapes and layerconfigurations described above, and the fluidic connector may be any ofthe soft or hard ports described above. In some embodiments, the kit mayfurther comprise a pump configured to connect to the fluidic connectorand transmit negative pressure to the wound dressing.

An example perforation pattern of a perforated cut 4515 is illustratedin FIG. 14B, which an enlarged view of the portion of FIG. 14A labeledwith the reference number 14B. In some embodiments, a repeatingperforation gap 4525 may extend across the perforation, each gapseparated by a connected or intact portion 4590. These perforation gaps4525 may extend through some or all of the layers of the sealing stripassembly described further below. In some embodiments, a perforation gap4525 may be 10 mm, or approximately 10 mm, in length, wherein length isthe dimension measured along the perforation line. The perforation gaplength may be also in the range of 2 mm to 20 mm, or approximately 2 mmto approximately 20 mm, in some embodiments. The intact portion 4590separating perforation gaps may be in the range of 0.25 mm to 3 mm, orapproximately 0.25 mm to approximately 3 mm, in length, for example 0.5mm, or approximately 0.5 mm, in length.

As shown in FIGS. 14C and 14D (which are side or cross-sectional viewsof FIG. 14A), the sheet 4500 of sealing strips 4501, or an individualsealing strip 4501, may comprise an adhesive film 4545, which may be aflexible film material provided with a pressure-sensitive adhesive on alower surface thereof. The adhesive film 4545 may, in some embodiments,be thin and prone to sticking to itself when folded or handled.Therefore, the adhesive film 4545 may be provided with a carrier layer4535 on an upper, non-adhesive surface having the same length and widthas the adhesive film 4545, and may also be provided with a one orprotective layers 4570, 4580 on its lower, adhesive surface. Theprotective layers 4570, 4580 may be configured to protect the adhesivesurface of the adhesive film 4545. First and second outer protectivelayers 4570 may be provided at opposite ends of the sheet 4500 or anindividual sealing strip assembly 4501 (on the right and left sides ofFIGS. 14A and 14C, with only the right side shown in FIG. 14D), therebycovering the opposite ends of the individual sealing strips 4501. Acentral protective layer 4580 may be provided over a central portion ofthe sheet 4500 or an individual sealing strip assembly 4501 andtherefore over a central portion of adhesive film 4545, between theopposite ends of the adhesive film 4545 and partially overlapping withand underlying the outer protective layers 4570. As illustrated, theprotective layers 4570 may have an outer edge (shown on the right inFIG. 14D) that is positioned beyond the outer edge of the adhesive film4545, and may also include a folded handle 4575 that is covered by thecentral protective layer 4580. The folded handles 4575 of protectivelayer 4570 are therefore not in direct contact with the adhesive surfaceof the adhesive film 4545 to facilitate removal of the outer protectivelayers 4570. Similarly, the portions 4585 of the central protectivelayer 4580 overlapping the outer protective layers 4570 are not indirect contact with the adhesive surface of the adhesive film 4545, andare not adhered to the outer protective layers 4570, thereby forminghandles to facilitate removal of the central protective layer 4580.

The carrier layer 4535 that may be provided on the upper surface of theadhesive film may be configured to releasably attach to the non-adhesivesurface of the adhesive film 4545, and may comprise a sheet of paper orfilm with relatively more rigidity than the adhesive film. Release tabs4595 may be provided on one or both opposite ends of the carrier layer4535 for ease of removing the carrier layer 4535 from the adhesive film4545. As illustrated in FIG. 14D, the release tabs 4595 may extendoutwardly from the adhesive film 4545 and carrier layer 4535 to an outeredge aligned with an outer edge of the outer protective layer 4570. Insome embodiments, graphical and/or numbered instructions for removal ofthe protective layer and carrier layer may be provided on one or both ofthe protective layer and carrier layer.

To utilize the sealing strips as described above, one or more sealingstrips 4501 may be removed from the sheet 4500 by cutting or tearingalong the perforations 4515. The central protective layer 4580 may beremoved using the non-adhered portions 4585 of the central protectivelayer 4580, which serve as handles, for the exposing a central adhesivesurface of the adhesive film 4545. The adhesive surface may then beapplied to skin and/or a dressing or any desired location, or theadhesive surface may be applied after one or both of the outerprotective layers 4570 is removed. The folded handle 4575 of outerprotective layers 4570 may be grasped to remove the outer protectivelayers 4570, exposing the entirety of the lower adhesive surface of theadhesive film 4545. The outer edges of the adhesive surface of theadhesive film 4545 may be placed in a desired location. After sealingthe adhesive film 4545, the release tab or tabs 4595 may be used toremove the carrier layer 4535 from the adhesive film 4545. This may berepeated with as many adhesive strips as are needed.

FIG. 14A illustrates a top view of assembly sheet 4500 of sealing stripassemblies 4501, in which the release tabs 4595 and carrier layer 4535on adhesive film 4545 would be seen. The dashed lines in FIG. 14Aillustrate edges or fold locations of the adhesive film 4545, centralprotective layer 4580, outer protective layers 4570, and carrier layer4535. In some embodiments, each sealing strip 4501 may have a width 4530of 40 mm, or approximately 40 mm, or a width in the range of 20 mm to 80mm, or approximately 20 mm to 80 mm. The overall length 4510 of eachsealing strip assembly (or the sheet 4500, including release tabs 4595and outer protective layers 4570) may be 250 mm or 300 mm in someembodiments, or approximately 250 mm or approximately 300 mm, or in therange of 100 mm to 400 mm, or approximately 100 to approximately 400 mm.The length 4520 of the adhesive film 4545 and carrier layer 4535 may be280 mm or 330 mm in some embodiments, or approximately 280 mm orapproximately 330 mm, or in the range of 90 mm to 380 mm, orapproximately 90 to approximately 380 mm. The length 4505 of centralprotective layer 4580 may be 210 mm or 260 mm in some embodiments, orapproximately 210 mm or approximately 260 mm, or may be in the range of100 mm to 300 mm, or approximately 100 mm to approximately 300 mm.

The length 4565 of outer protective layers 4570 (not including thefolded portion) may be 85 mm or 110 mm in some embodiments, orapproximately 85 mm or approximately 110 mm, or may be in the range of50 mm to 200 mm, or approximately 500 mm to approximately 200 mm. Thelength 4555 of the folded portion or handle 4575 of outer protectivelayer 4570 may be 20 mm plus or minus 5 mm, in some embodiments, orapproximately 20 mm plus or minus approximately 5 mm. The distance 4550from the outer edge of the folded tab 4575 to the outer edge of thecentral protective layer 4580 may be 20 mm plus or minus 5 mm, in someembodiments, or approximately 20 mm plus or minus approximately 5 mm.

VII. Overview of Example Negative Pressure Delivery Testing

FIGS. 15A-15L illustrate differential pressure results of dry testingvarious materials for bridge sections of a dressing such as describedherein, and FIGS. 16A-16C illustrate differential pressure results ofwet testing various materials. The testing methodology was designed toassess the ability of dressing bridges to deliver negative pressure.

A wound model plate was constructed for both wet and dry testing of thesample dressings. In this testing embodiment, the wound model plate wasan aluminum flat plate, however other materials can also providesuitable testing models. Two 2 mm±1 mm diameter holes were formed in thewound model plate to act as ports for negative pressure delivery andtesting, with a first hole along a center line for placement of a sampledressing. A first segment of each hole was drilled in from the side ofthe plate, and a second segment connecting to the first segment wasdrilled in through the top of the plate. The path length from hole tohole (center to center) was approximately 22 mm±1 mm, corresponding to aminimum path length hole to hole (between proximal edges) ofapproximately 20 mm±1 mm. Other implementations of the testing methodcould reposition the port locations and distance. This testing modelallows a negative pressure pump with settable pressures, for exampleRENASYS EZ in one embodiment, to draw negative pressure at a given setpoint down a first tube with a first in-line pressure sensor. This tubefeeds into a first of the two ports. A second tube with a second in-linepressure sensor is arranged in a second of the two ports with a massflow controller. The mass flow controller is capable of introducing acontrolled leak into the system. As it is desirable to consider the leakrate as a function of volume per unit time, volume was set on the massflow meter in units of standard cubic centimeters per minute(scc/minute, which can also abbreviated to scc/m, scc/min or sccm). Anysettable gas leak generator can be used in other testingimplementations.

Each sample dressing was created having a wound contact layer, a coverlayer, and the material or layered materials to be tested sandwichedbetween the wound contact layer and the cover layer. The wound contactlayer and cover layer were sealed together around the material having aperimeter width of at least 2.5 cm or, in other embodiments,approximately 5 to 10 cm, where the width is measured from the innermaterials to the edge of the sealed border. It will be appreciated,according to the layer material descriptions provided herein, that someof the materials tested can be “sided,” that is asymmetric along avertical axis. Accordingly, tested sample dressings were constructedwith specific orientations of sided materials consistent with thematerial descriptions herein, though other orientations of the sidedmaterials could be suitable for use in wound dressings.

For testing of the various sample dressings, each sample dressing samplewas placed on the wound model with the first port approximately locatedalong a center line of the dressing. The wound contact layer adhered tothe wound model plate covering both of the first and second ports withthe material to be tested so that negative pressure could be deliveredto the material through the first port, so that a level of negativepressure within the material could be tested at the second port.

For each sample tested, a positive control was provided using an emptytube provided to connect the first port to the second port. In oneimplementation, the empty tube comprised a clear and flexible PVC tube,single bore with circular cross section, internal diameter ofapproximately 1.6 mm, outer diameter of approximately 3.2 mm and lengthof approximately 65 mm. The ends of this tube were pushed into the woundmodel ports affording snug fits between the outer surfaces of the tubeand the inner surfaces of the ports.

For each sample the pressure differential between the two in-linesensors, i.e. the pressure drop across the sample, was measured at avariety of set points. The tested set points were 0, −60, −100, −140 &−200 mmHg, but the set points could be set to other values in otherembodiments of the bridge testing. An air leak was introduced to eachtested sample. In some tests, an air leak of approximately 16 scc/minutewas introduced to represent what a negative pressure pump, for examplePICO, can typically experience during its maintenance cycles. Forexample, negative pressure pumps can handle between about 12 scc/minuteto about 20 scc/minute, with 16 scc/minute representing the average. Inother tests, an air leak of approximately 50 scc/minute was introducedto test conditions approximating the 300 scc/minute to 350 scc/minuteleak experienced during pump down. Other tests could be structured totest higher air leak rates as needed.

In order to calculate the pressure differential, first the positivecontrol was measured.

The tests that were conducted, as discussed with respect to FIGS.15A-15L, only allowed air into the system. Dealing with liquids such aswound exudate or irrigation fluids whilst simultaneously deliveringnegative pressure presents a different challenge to the bridges and isnot accounted for in the test data of FIGS. 15A-15L. The test data ofFIGS. 16A-16J accounts for liquid introduced into the tested system.

An embodiment of a dry differential pressure testing method, asimplemented to produce the test data of FIGS. 15A-15L, can include thefollowing steps:

-   -   1. Set-up the wound plate with the first hole connected to the        pump via a gas pressure sensor and the second hole connected to        the settable air leak via a second pressure sensor.    -   2. Stick the pad of a self-adhesive dressing sample across the        two holes on the top of the plate so that the pad traverses        across the two holes.    -   3. Zero each gas pressure sensor.    -   4. Record initial pressure differential (negative pressure side        minus leak side).    -   5. Set air leak to 16 scc/minute and run pump at −60 mmHg        negative pressure.    -   6. After 30 seconds, record pressure differential (negative        pressure side minus leak side).    -   7. Record pressure differentials at set point pressures of −100,        −140 and −200 mmHg in addition to −60 mmHg.    -   8. Record initial pressure differential (negative pressure side        minus leak side).    -   9. Set air leak to 50 scc/minute and run pump at −60 mmHg        negative pressure.    -   10. After 30 seconds, record pressure differential (negative        pressure side minus leak side).    -   11. Record pressure differentials at set point pressures of        −100, −140 and −200 mmHg in addition to −60 mmHg.    -   12. Repeat for all test samples.

An embodiment of a wet differential pressure testing method, asimplemented to produce the test data of FIGS. 16A-16C, can include thefollowing steps:

-   -   1. Set-up the wound plate with the first hole connected to the        pump via a gas pressure sensor and the second hole connected to        the settable air leak via a second pressure sensor.    -   2. Stick the pad of a self-adhesive dressing sample across the        two holes on the top of the plate so that the pad traverses        across the two holes.    -   3. Replace leak tube with a syringe containing 5.4 g saline.    -   4. Switch on pump (set to approximately −80 mmHg) to deliver        negative pressure to the sample.    -   5. Allow substantially all of the saline to pass through the        sample over approximately a 5 minute period.    -   6. Remove syringe and allow negative pressure to evacuate liquid        from sample and tubes if unblocked, and otherwise leave saline        in the sample and tubes, then turn pump off    -   7. Reattach leak tube with its pressure sensor.    -   8. Zero each gas pressure sensor.    -   9. Record initial pressure differential (negative pressure side        minus leak side).    -   10. Set air leak to 16 scc/minute and run pump at −60 mmHg        negative pressure.    -   11. After 30 seconds, record pressure differential (negative        pressure side minus leak side).    -   12. Record pressure differentials at set point pressures of        −100, −140 and −200 mmHg in addition to −60 mmHg.    -   13. Record initial pressure differential (negative pressure side        minus leak side).    -   14. Set air leak to 50 scc/minute and run pump at −60 mmHg        negative pressure.    -   15. After 30 seconds, record pressure differential (negative        pressure side minus leak side).    -   16. Record pressure differentials at set point pressures of        −100, −140 and −200 mmHg in addition to −60 mmHg.    -   17. Repeat for all test samples.

Prior to each run or prior to each day of testing, the in-line pressuresensors can be calibrated and the same data for a negative control (topplate holes blocked with self-adhesive film) and positive control (opentube connecting the two top holes in the plate) can be recorded.

An embodiment of a data processing method for calculating and plottingthe negative pressure differential across a portion of a sample dressingat different set points can include the following steps:

-   -   1. Zero adjustment—for each individual run (including controls        and test samples) subtract the zero pressure reading from each        of the data readings in that run.    -   2. Baseline correction—to each (zero adjusted) data point in a        test sample run subtract the (zero adjusted) positive control        data point at the corresponding pressure setting.    -   3. Plot set pressure versus recorded differential pressure        (after subtraction of zero pressure readings and subtraction of        positive control).

The charts illustrated in FIGS. 15A-15L and 16A-16J will be discussed inconjunction with the Table 1, below, that includes the material orlayered materials represented by the numbered legends in FIGS. 15A-15Land 16A-16J. For at least some of the tested material or materialsindicated by the various legend numbers in Table 1, the dimensions ofheight, width, and cross sectional area specified may be approximate.For example, two, three, or more sample dressings of approximately thesame dimensions were made for at least some of the tested materials, andthe listed dimensions represent an approximation of a mean value of thematerial dimensions for the sample dressings tested for that material.In addition, all sample measurements were taken using calibrated digitalcalipers. In the case of compressible materials, the measurementsreported are those of the uncompressed materials. Where variations inheight readings were noted on a compressible material, height wasrecorded at 3 points along the fluid path and the mean was reported. Inall cases width was recorded at 3 points along the fluid path and themean reported. In considering the mean width of a sample it is implicitthat the variation in width between readings is tolerable without anysignificant narrowings or constrictions along the fluid path.

As used in Table 1, “spacer” refers to an embodiment of spacer layermaterial of 200-220 g/m² (or approximately 200-220 g/m²) Baltex 3D-knitfabric. DryWeb TDL2 refers to a 55 gsm (or approximately 55 gsm)Libeltex BVBA material that can be used for an ADL in the dressingsdescribed herein. SlimCore TL4 refers to a 150 gsm (or approximately 150gsm) Libeltex BVBA material that can also be used for an ADL in thedressings described herein. Another possible ADL material tested andlisted in Table 1 is MH080.121 a Glatfelter material slit to a width of250 mm or approximately 250 mm. MH460.101 refers to a 460 gsm (orapproximately 460 gsm) Glatfelter superabsorbent material that can beslit to a width of 250 mm. Masking layer, as used in Table 1, refers toa 70 gsm (or approximately 70 gsm) Don & Lowe blue woven material.DT360.100 refers to an approximately 360 gsm Glatfelter superabsorbentairlaid material including cellulose fibers with superabsorbentparticles. Reticulated PU foam refers to an open-cell polyurethane foam,while PU foam refers to an open-cell foam that has not been reticulated.The configuration of dressing sample 347306 approximates the layerconfiguration illustrated in FIGS. 4A-4D. Basis weights reported referto nominal basis weights and typically have a ±10% tolerance. “Stack”refers to the testing of multiple materials in a single arrangement.Where multiple materials were tested in one sample dressing, thematerials are listed in order of top to bottom, for the testedarrangement.

TABLE 1 Mean Mean Mean cross height width sectional Legend No.Material(s) (mm) (mm) area (mm2) 346601—3D Baltex 7970, weft knittedpolyester spacer 2 14 27 Spacer Fabric layer fabric, 210 gsm 346602—3DBaltex 7970, weft knitted polyester spacer 2 3 7 Spacer Fabric layerfabric, 210 gsm 346603—3D Baltex 7970, weft knitted polyester spacer 2 13 Spacer Fabric layer fabric, 210 gsm 346604—Super- Glatfelter Inc.,DT360.100, thermally bonded 4 4 14 absorber air-laid withsuper-absorbent powder and cellulose fibres, 360 gsm 346605— Smith &Nephew, RENASYS-F Foam, 5 3 15 Reticulated Foam reticulated, open-cell,polyurethane foam 346606— Smith & Nephew, RENASYS-F Foam, 5 7 36Reticulated Foam reticulated, open-cell, polyurethane foam 347201—ADLLibeltex BVBA, SlimCore TL4, triple layered 2 11 27 ADL, hydrophilic PETand bicomponent fibres, through air bonded web, 150 gsm 347202—ADLLibeltex BVBA, SlimCore TL4, triple layered 2 4 10 ADL, hydrophilic PETand bicomponent fibres, through air bonded web, 150 gsm 347204—ADLLibeltex BVBA, DryWeb TDL2, through air 2 21 40 bonded web, 55 gsm347205—ADL Libeltex BVBA, DryWeb TDL2, through air 1 3 3 bonded web, 55gsm 347206—3D Baltex 7970, weft knitted polyester spacer 2 15 31 SpacerFabric layer fabric, 210 gsm 347207—Stack Libeltex BVBA, SlimCore TL4,triple layered 3 18 51 ADL, hydrophilic PET and bicomponent fibres,through air bonded web, 150 gsm Baltex 7970, weft knitted polyesterspacer 2 14 26 layer fabric, 210 gsm (smaller footprint than ADL)347301—Stack Libeltex BVBA, DryWeb TDL2, through air 1 22 28 bonded web,55 gsm Baltex 7970, weft knitted polyester spacer 2 12 24 layer fabric,210 gsm (smaller footprint than ADL) 347302—Masking Don & Low Ltd NonWovens, PP non woven 0.4 14 6 Layer fabric, blue, thermally bonded, 70gsm 347303—Stack Don & Low Ltd Non Wovens, PP non woven 0.4 15 6 fabric,thermally bonded, 70 gsm Baltex 7970, weft knitted polyester spacer 2 1120 layer fabric, 210 gsm(smaller footprint than masking layer)347304—super- Glatfelter Falkenhagen GmbH, MH460.101, 2 10 18 absorbermultibonded airlaid nonwoven containing super-absorbent powder,laminated against cellulose tissue, 460 gsm 347305—Super- GlatfelterFalkenhagen GmbH, MH460.101, 2 3 6 absorber multibonded airlaid nonwovencontaining super-absorbent powder, laminated against cellulose tissue,460 gsm 347306—Stack Don & Low Ltd Non Wovens, PP non woven 0.4 14 6fabric, blue, thermally bonded, 70 gsm Glatfelter Falkenhagen GmbH,MH460.101, 2 14 25 multibonded airlaid nonwoven containingsuper-absorbent powder, laminated against cellulose tissue, 460 gsmGlatfelter Falkenhagen GmbH, MH080.121, 1 15 11 multibonded airlaidnonwoven Baltex 7970, weft knitted polyester spacer 2 11 19 layerfabric, 210 gsm (smaller footprint than upper layers) 347308—ADLGlatfelter Falkenhagen GmbH, MH080.121, 1 15 11 multibonded airlaidnonwoven 347309—ADL Glatfelter Falkenhagen GmbH, MH080.121, 1 5 4multibonded airlaid nonwoven 347310—Super- Glatfelter Inc., DT360.100,thermally bonded 3 14 47 absorber air-laid with super-absorbent powderand cellulose, 360 gsm 347311—Stack Glatfelter Inc., DT360.100,thermally bonded 3 14 46 air-laid with super-absorbent powder andcellulose fibres, 360 gsm Baltex 7970, weft knitted polyester spacer 210 18 layer fabric, 210 gsm (smaller footprint than upper layer) 347312—Smith & Nephew, Allevyn foam, from bulk, 10 10 99 Absorbent Foam with anon-adhesive perforated wound contact layer (WCL) laminated to the topand bottom surfaces (WCL is the same as applied to the ProGuide WoundContact Layer (WCL) surfaces) 347313—Stack Glatfelter Inc., DT360.100,thermally bonded 4 11 40 air-laid with super-absorbent powder andcellulose fibres, 360 gsm Smith & Nephew, RENASYS-F Foam, 5 10 52reticulated, open-cell, polyurethane foam 349301—ADL Shalag Nonwovens,ST6CTPH90G, ADL, 90 2 10 24 gsm (longitudinal axis of the sample in linewith the visually predominate fibre orientation of the distributionlayer. Distribution layer orientated next to top film.) 349302—ADLShalag Nonwovens, STAHTCT8OL, ADL, 80 1 11 16 gsm (Distribution layerorientated next to top film.) 349303—ADL Shalag Nonwovens, ST6CT8H65,ADL, 65 3 9 26 gsm (Distribution layer orientated next to top film.)349304—ADL Shalag Nonwovens, ST6NT8H75, ADL, 75 4 10 44 gsm(Distribution layer orientated next to top film.) 349305—3D Apex Mills,3D Spacer Fabric, DNB198A, 2 10 21 Spacer Fabric polyester, 270 gsm(Face with larger holes orientated next to top film) 349306—3D ApexMills, 3D Spacer Fabric, DNB197, 6 10 60 Spacer Fabric polyester, 670gsm 349307—3D Heathcote Fabrics Limited, SpaceTec, 2.5 mm 3 10 25 SpacerFabric gauge, polyester, 430 gsm (Face with larger holes orientated nextto top film) 349308—3D Heathcote Fabrics Limited, SpaceTec, 3 mm 3 10 30Spacer Fabric gauge, polyester, 320 gsm (Face with larger holesorientated next to top film) 349309—3D Apex Mills, 3D Spacer Fabric,DNB22(6), 3 9 29 Spacer Fabric polyester (Face with larger holesorientated next to top film) 349310—ADL Libeltex BVBA, DryWeb T28F,monolayered 1 10 14 AQL, hydrophilic PET and bicomponent fibres, throughair bonded web, 50 gsm 349311—ADL Libeltex BVBA SlimCore TL4, triplelayered 3 10 29 ADL, hydrophilic PET and bicomponent fibres, through airbonded web, 90 gsm 410502— Smith & Nephew, RENASYS-F Foam, 5 10 53Reticulated Foam reticulated, open-cell, polyurethane foam 410503— Smith& Nephew, Allevyn foam, from bulk 6 10 61 Absorbent Foam 410504—MaskingDon & Low Ltd Non Wovens, PP non woven 0 10 5 Layer fabric, blue,thermally bonded, 70 gsm 410505— Smith & Nephew, RENASYS-F Foam, 10 10100 Reticulated Foam reticulated, open-cell, polyurethane foam410506—PVA KCI, WhiteFoam, prehydrated open cell PVA 10 10 96 Foam foam(prehydrated) 411201—Stack Glatfelter Inc., DT360.100, thermally bonded4 14 57 air-laid with super-absorbent powder and cellulose fibres, 360gsm Smith & Nephew, RENASYS-F Foam, 11 10 106 reticulated, open-cell,polyurethane foam (smaller footprint than upper layer) 411202—StackGlatfelter Inc., DT360.100, thermally bonded 4 15 57 air-laid withsuper-absorbent powder and cellulose fibres, 360 gsm Smith & Nephew,RENASYS-F Foam, 13 10 131 reticulated, open-cell, polyurethane foam(smaller footprint than upper layer)

A top film of EU33 PU IV3000 film with a K5 pattern spread was typicallyused for the top film of each tested sample dressing in Table 1, withthe exception of samples that failed due to puncture that werereinforced with EU30 Opsite Flexigrid over the leaks, as well as thesample dressing 347206 that replaced the EU33 PU IV3000 film with thethicker, tougher, and less hydrophilic EU30 Opsite Flexigrid. Perforatedsilicone, specifically A8/EU30 PU film, was used for the wound contactlayer. However, the dressings disclosed herein are not limited to theuse of these materials for the top film and the wound contact layer, asany materials with similar properties to those tested can be implementedin various embodiments.

The tested materials were deemed to satisfy the testing criteria and besuitable for bridges if able to maintain negative pressure transmissionunder typical ranges of negative pressure. For example, one pumpoperates in a range of approximately −60 mmHg to −100 mmHg, and anotherpump embodiment operates in a range of approximately −60 mmHg to −200mmHg. According to first testing criteria, a tested material was deemedto fail, or be unsuitable for bridges, if when assessed against a setpoint pressure in the range −60 to −200 mmHg with an air leak of 50scc/minute a negative pressure less than approximately −40 mmHg (thatis, closer to zero) was being transmitted to any intended part of thedressing. According to second testing criteria, materials having apressure differential of approximately −25 mmHg or less (that is, closerto zero) at a set point of −200 mmHg with a leak rate of 50 scc/minutewere determined to be clinically appropriate. According to third testingcriteria, materials having a pressure differential of approximately −5mmHg or less (that is, closer to zero) at a set point of −200 mmHg witha leak rate of 50 scc/minute were determined to be clinicallyappropriate. Such testing criteria account for the possibility that testresults can include noise of ±3 mmHg.

One of the above testing criteria can be selected to determineappropriate materials for a particular dressing based on a variety ofcharacteristics of the dressing including dressing shape, dressingdimensions, number of ports, port locations, number of bridges, bridgedimensions, or the like. As an example, the more robust transmissionmaterials satisfying the third testing criteria could be used in someembodiments for long dressings having multiple bridging portions toreduce the compounding pressure drop effects of multiple bridgingportions, for dressings with narrow bridges, dressings having a largenumber of bridges, or dressings having relatively long distances betweenports. As discussed above, multiple port locations along a long dressingcan also be used to maintain sufficient levels of negative pressure. Asanother example, materials satisfying the second criteria (and also themore restrictive first criteria) can be suitable for dressings withwider bridges, a greater number of ports, and/or smaller coverage areas.

Turning now to FIGS. 15A-15L, testing data for dry testing a pluralityof sample dressings at a plurality of pressure set points is illustratedfor test systems having air leaks of 16 scc/minute and 50 scc/minute,respectively.

Referring to FIG. 15A, the measured pressure differential (in mmHg) isillustrated for sample dressings 346601, 346602, 346603, 346604, 346605,346606, 347201, 347202, 347204, 347205, 347206, and 347207 as a functionof set negative pressure with a 16 scc/minute leak rate. Generally, if aspacer layer was in direct contact with the top film layer, the top filmlayer was punctured by the spacer layer filaments, producing a leak thatwas sealed using a layer of additional, thicker film to continue thetesting. Sample dressing 346604 experienced decreased negative pressuretransmission performance due to compression of the Airlaid SAP. Sampledressing 347205, constructed from Airlaid SAP having a smaller crosssectional area than the material used in sample dressing 346604,experienced failure due to compression of the Airlaid SAP under the setnegative pressure points. The other tested materials generally performedwell, as indicated by proximity of the corresponding plot line to thezero pressure differential axis.

FIG. 15B depicts the measured pressure differential of the same set ofsample dressings as in FIG. 15A, however as a function of set negativepressure with a 50 scc/minute leak rate. Generally speaking, the higherleak rate reduced the negative pressure transmission performance of alltested materials, however all of the illustrated sample dressingsmaintained satisfactory levels of negative pressure throughout thedressing with the exception of sample dressings 346604 and 347205.

Turning to FIG. 15C, the measured pressure differential of a second setof sample dressings is depicted as a function of set negative pressurewith a 16 scc/minute leak rate. The second set of sample dressingsincludes 347301, 347302, 347303, 347304, 347305, 347306, 347308, 347309,347310, 347311, 347312, and 347313 from Table 1. As illustrated by thecorresponding plot line, the masking layer tested in sample dressing347302 was not suitable for transmission of sufficient negative pressurelevels. The non-reticulated PU foam was also not suitable, asillustrated by the plot line corresponding to sample dressing 347312,and experienced significantly reduced performance as compared toreticulated PU foam. Dressing 347308, employing MH080.121, correspondsto a plot line trending downward, and the reduced-width MH080.121 ofsample dressing 347309 also experienced unsuitable levels of negativepressure due to the pressure differential.

FIG. 15D illustrates test results for the second set of sample dressingsalso depicted in FIG. 15C, however using a 50 scc/minute leak rate. Theplot lines of test data corresponding to sample dressings 347301,347303, 347306, 347311, and 347313 all remain close to the zero pressuredifferential axis, indicating good performance with respect to negativepressure transmission.

FIG. 15E illustrates the pressure differential at a set point negativepressure of −200 mmHg and 50 scc/minute leak rate after subtraction ofpositive control for each of the dry tested sample dressings.

Turning to FIG. 15F, the measured pressure differential of another setof sample dressings is depicted as a function of set negative pressurewith a 16 scc/minute leak rate. This set of sample dressings includes349301, 349302, 349303, 349304, 349305, 349306, 349307, 349308, 349309,349310 and 349311. With respect to both the ADL tested in sample 349303and the ADL tested in sample 349310, the corresponding plot linesdemonstrate that the pressure differential exceeds −5 mmHg at pointsacross the range of negative pressure set points assessed. Accordingly,such materials would not be most suitable for use as a transmissionlayer. The plot lines of test data corresponding to sample dressings349301, 349302, 349304, 349305, 349306, 349307, 349308, 349309 and349311 all remain close to the zero pressure differential axis,indicating good performance of the materials or stacks tested in thesesamples with respect to negative pressure transmission at the specifiedheights and widths.

FIG. 15G illustrates test results for the same set of sample dressingsdepicted in FIG. 15F, however using a 50 scc/minute leak rate. Withrespect to the ADL tested in sample 349310, the corresponding plot linedemonstrates that the pressure differential exceeds −5 mmHg at pointsacross the range of negative pressure set points assessed, in line withthe observation made for this sample at the lower leak rate. The plotlines of test data corresponding to sample dressings 349301, 349302,349303, 349304, 349305, 349306, 349307, 349308, 349309 and 349311 allremain close to the zero pressure differential axis, indicating goodperformance of the materials or stacks tested in these samples withrespect to negative pressure transmission at the specified heights andwidths.

Turning to FIG. 15H, the measured pressure differential of another setof sample dressings is depicted as a function of set negative pressurewith a 16 scc/minute leak rate. This set of sample dressings includes410502, 410503, 410504, 410505, 410506, 411201 and 411202. Asillustrated by the corresponding plot line an increase in the pressuredifferential was observed for sample 411201, a stack containing areticulated PU foam transmission layer with dimensions of 10 mm meanwidth and 11 mm mean height, at a set-point of −60 mmHg, however thisincreased pressure differential abated at higher negative pressure setpoints. Sample 411202, a stack containing a reticulated PU foamtransmission layer with slightly larger dimensions of 10 mm mean widthand 13 mm mean height did not follow a similar trend to 411201 andshowed no significant increase in pressure differential across the rangeof negative pressure set points tested. As illustrated by thecorresponding plot line an increase in the pressure differential wasobserved for sample 410503, containing an absorbent PU foam. Asillustrated by the corresponding plot line an increase in the pressuredifferential was observed for sample 410504, containing a masking layer,this result was probably driven largely by the fact that the maskinglayer has such a low profile (0.4 mm mean height). As illustrated by thecorresponding plot line an increase in the pressure differential wasobserved for sample 410506 a prehydrated PVA foam, and according to thetesting criteria this material appeared acceptable at negative pressureset points up to and including −100 mmHg but then demonstrated asignificant increase in the pressure differential at negative pressureset points above this. The plot lines of test data corresponding tosample dressings 410502, 410505 and 411202 all remain close to the zeropressure differential axis, indicating good performance with respect tonegative pressure transmission at the specified heights and widths foreach material or stack.

FIG. 15I illustrates test results for the same set of sample dressingsdepicted in FIG. 15H, however using a 50 scc/minute leak rate. Withrespect to the absorbent PU foam tested in sample 410503, the maskinglayer tested in sample 410504, and the prehydrated PVA foam tested insample 410506, the corresponding plot lines demonstrate that thepressure differential exceeds −5 mmHg at points across the range ofnegative pressure set points assessed, in line with the observation madefor this sample at the lower leak rate. As illustrated by thecorresponding plot line an increase in the pressure differential wasobserved for sample 411201, a stack containing a reticulated PU foamtransmission layer with dimensions of 10 mm mean width and 11 mm meanheight, at a set-point of −60 mmHg, however this increased pressuredifferential abated at higher negative pressure set points, consistentwith the observation made for this sample at the lower leak rate. Theplot lines of test data corresponding to sample dressings 410502, 410505and 411202 all remain close to the zero pressure differential axis,indicating good performance with respect to negative pressuretransmission at the specified heights and widths for each material orstack.

Turning now to FIG. 15J, a comparison graph illustrates the performanceof all samples, normalized to a width of 10 mm±1 mm, as a function ofset negative pressure with a 16 scc/minute leak rate when dry tested.FIG. 15K illustrates test results for the same set of sample dressingsdepicted in FIG. 15J, however using a 50 scc/minute leak rate.Accordingly, FIGS. 15J and 15K allow for relative comparison of sampleperformance at a standardized width across the samples. Similar to theother pressure differential charts discussed herein, suitabletransmission layer materials will demonstrate a pressure differentialaround or below approximately −5 mmHg at points across the range ofnegative pressure set points assessed.

FIG. 15L illustrates the pressure differential at a negative pressureset point of −200 mmHg and 50 scc/minute leak rate after subtraction ofpositive control for each of the width-normalized dry tested sampledressings of FIGS. 15J and 15K. Materials suitable for transmissionlayers, or stacks including at least one suitable transmission layer,are indicated by plots illustrating that a pressure differential of−160.0 mmHg or less was recorded. This can correspond to delivery of atleast −40 mmHg therapy against a set point in the range −60 to −200 mmHgwith an air leak of 50 scc/minute. In some scenarios, −40 mmHg canrepresent the minimum clinically acceptable level of wound therapy.Accordingly, delivery of less than −40 mmHg can result in clinicallyunacceptable levels of wound therapy in some scenarios. [0193] Asindicated by the test results of FIGS. 15A-15L and the materialspecifications of Table 1, generally speaking, a dressing implementingthe 3D knit spacer layer or reticulated foam as a transmission layerwill experience low negative pressure differentials across bridgingportions with widths as low as approximately 1 mm. Smaller widths than 1mm using these materials, though possible for sufficient negativepressure transmission, were not included in the testing data due tolimitations of the sample dressing construction process. Dressingembodiments implementing a non-woven transmission layer for bridgingportions, such as the Libeltex ADL materials, can also experience lownegative pressure differentials. In addition, materials suitable forbridging portions have good resiliency, in that such materials reboundafter compression to allow for transmission of negative pressure. Othermaterials, in addition to the samples tested, offering the desiredpermeability to gas and liquid at a set width and/or height while undercompression due to negative pressure can be suitable for use as atransmission layer.

Table 2 illustrates the raw data used to generate the charts of FIGS.15A-15L.

TABLE 2 Leak rate (scc/min) Leak rate (scc/min) 16 50 Pressures (mmHg)Pressures (mmHg) 0 60 100 140 200 0 60 100 140 200 Ref Recorded dP(mmHg) Day 1 Positive Control −0.1 −2.8 −4.5 −6.3 −8.9 −0.1 −3.1 −4.9−6.7 −9.2 346601 0.1 −2.9 −4.6 −6.4 −9 0.2 −2.9 −4.8 −6.6 −9.2 3466020.7 −2.6 −4.5 −6.4 −9.3 −0.7 −2.9 −4.8 −6.8 −9.8 346603 0.2 −2.9 −4.8−6.7 −9.8 0.3 −3.4 −5.7 −8.1 −12.4 346604 0 −3.3 −5.6 −8.9 −13.2 0 −5.9−13.2 −176.3 346605 −3 −6.2 −8.2 −10.3 −13.7 −2.8 −7.6 −10.4 −13.3 −18346606 −3 −6.6 −8.5 −10.4 −13.4 −3 −6.8 −9 −11.1 −14.6 347201 0 −3.2 −5−6.9 −9.7 0.2 −3.6 −5.7 −7.7 −10.8 347202 0.2 −3.2 −5.2 −7.2 −10.3 0.4−4.4 −6.9 −9.3 −13 347204 0.2 −3.3 −5.4 −7.4 −10.3 0.3 −4.3 −6.9 −9.2−12.6 347205 0 −6.7 −16 −15.3 −22.7 0.4 20.2 −29.2 −39 −55.5 347207 0.1−3.1 −5 −6.9 −9.6 0.2 −3.4 −5.3 −7.2 −10 347206 0.1 −3.5 −5.6 −7.6 −10.70.2 −4.9 −6.8 −9 −12.1 Day2 Negative Control 0 −65.7 −108.6 −150.6 >−200Positive Control −0.1 −3.2 −5.1 −7 −9.8 0.2 −3.2 −5.2 −7.1 −9.9 347301−0.1 −3.2 −5.2 −7.1 −9.9 0 −3.4 −5.3 −7.2 −10 347302 −0.1 −12 −16.8−19.5 −32.5 −0.1 −19 −32.5 −40.4 −53.1 347305 −0.1 −4.7 −7.8 −10.7 −15−0.1 −9.6 −15 −19.8 −26.5 347304 −0.2 −4.3 −6.5 −8.6 −11.8 0 −6.9 −9.6−12.1 −16 347303 0 −3.3 −5.2 −7.1 −9.9 0.2 −3.3 −5.3 −7.2 −10 347306 0.1−3.1 −5.1 −7 −9.8 0.2 −3.2 −5.2 −7.1 −10 347308 0.2 −4.8 −9.7 −10.8−14.8 0.2 −11.7 −14.3 −17 −23.3 347309 0.1 −6.1 −9 −12.1 −17.1 0.2 −13.2−18.2 −23.6 −32.2 347310 0.1 −6.5 −7.7 −9.8 −13.2 0.1 −7.4 −9 −11.3−15.2 347311 0.1 −3.2 −5.2 −7.1 10 0.1 −3.3 −5.4 −7.3 −10.2 347312 0−4.9 −8.6 −13.5 −23.4 0 −8.8 −17.7 −28.5 −48.6 347313 0 −3.3 −5.3 −7.2−10.1 0 −3.5 −5.6 −7.5 −10.6 Day 4 Negative Control 0 −64 −105 — >−200Positive Control 0 −1 −1.1 −1.4 −2 −0.1 −0.8 −0.8 −1 −1.6 349301 0 −1.5−1.8 −2.2 −2.7 0.1 −1.2 −1.6 −2.2 −3.2 349302 0 −0.6 −1 −1.5 −2.2 0.1−1.2 −1.7 2.3 −3.3 Day 5 Negative Control 0.1 −62.8 −104.2 −144.1 >−200Positive Control 0.1 0.4 0.7 1 1.5 0 0.2 0.5 0.8 1.3 349303 0 −4.7 −5.8−6 −5.1 0 0.2 0.3 0.3 −0.4 349304 −0.1 0.3 0.4 0.7 0.9 0 0.5 0.5 0.4 0.2349305 −0.2 0.4 0.7 1 1.2 −0.1 −0.1 −0.2 −0.5 −0.8 349306 −0.1 0.3 0.60.9 1.4 −0.2 −3.8 −2 −1.5 −1.8 349307 −0.2 −1 −0.5 −0.2 0.6 0.1 −2.8−2.1 −1.7 −1.2 349308 −0.1 1 1.5 2 2.5 −0.2 −0.3 0.4 0.7 1.1 349309 00.7 1.1 1.4 1.8 0.2 −1 −0.3 −0.1 0 349310 0 −9.6 −9.8 2 −2 −0.2 −3.9−4.7 −5.9 −6.2 349311 −0.1 1 1.7 2.9 3.3 0.1 0.7 0.6 0.6 0.5 Day 6:Negative Control 0.1 −62.7 −103.7 −143.8 >−200 Positive Control 0.1 0.10.1 0.1 −0.1 0.3 0.6 0.5 0.5 0.3 410502 0.2 0.2 0.2 0.1 −0.3 0.3 0.1 0−0.3 −0.8 410503 0.4 −1.8 −5.8 −11.3 −24.5 0.5 −7.3 −17.8 −31.5 −56.8410504 0.4 −2.3 −3.8 −5.4 −8.3 0.2 −11.4 −14.2 −17.8 −26 410505 0.2 0 0−0.1 −0.4 0.3 0.3 0.3 0.3 0.2 410506 0.2 0.2 −0.3 −9 −29 0.1 −0.7 −2 −7−34 Day 7 Negative Control 1.4 −60.6 −101.4 −141.2 >−200 PositiveControl 1.3 0.5 0.3 0.2 0 0.5 0.3 0.2 0.1 −0.1 411201 1.3 −5 −2.2 −0.40.6 1.8 −7.5 −2.8 −1.1 −0.5 411202 1.8 0.3 0.2 0 −1.1 2.1 −1 −1.3 −1.9−2.4

Turning now to FIGS. 16A-16J, testing data for wet testing a pluralityof sample dressings at a plurality of pressure set points is illustratedfor test systems having air leaks of 16 scc/minute and 50 scc/minute,respectively.

Referring specifically to FIGS. 16A-16B, testing data for wet testing aplurality of sample dressings at a plurality of pressure set points isillustrated for test systems having air leaks of 16 scc/minute and 50scc/minute, respectively. The samples of FIGS. 16A and 16B include asubset of the samples tested for FIGS. 15A and 15B, illustrating theperformance of samples 346604, 346605, 346606, 347304, and 347201. Asillustrated by the plot lines corresponding to the tested materials, theSlimCore TL4 of sample 347201 as well as two tested widths of thereticulated foam of samples 346605 and 346606 provided clinicallyappropriate pressure transmission even with wet testing.

FIG. 16C illustrates the pressure differential at a negative pressureset point of −200 mmHg and 50 scc/minute leak rate after subtraction ofpositive control for each of the wet tested sample dressings.

Turning to FIG. 16D, the measured pressure differential of the set ofsample dressings of FIGS. 15F and 15G is depicted as a function of setnegative pressure with a 16 scc/minute leak rate. This set of sampledressings includes 349301, 349302, 349303, 349304, 349305, 349306,349307, 349308, 349309, 349310 and 349311. With respect to the ADLtested in sample 349310, the corresponding plot line demonstrates thatthe pressure differential exceeds −5 mmHg at least at one point acrossthe range of negative pressure set points assessed. The plot lines oftest data corresponding to all other sample dressings remain close tothe zero pressure differential axis, indicating good performance of thematerials or stacks tested in these samples with respect to negativepressure transmission at the specified heights and widths when wet.

FIG. 16E illustrates test results for the same set of sample dressingsdepicted in FIG. 16D, however using a 50 scc/minute leak rate. Withrespect to the materials tested in samples 349301, 349302, 349303,349306 and 349310, the corresponding plot lines demonstrate that thepressure differentials exceed −5 mmHg at least at one point across therange of negative pressure set points assessed. The plot lines of testdata corresponding to sample dressings 349304, 349305, 349307, 349308,349309 and 349311 all remain close to the zero pressure differentialaxis, indicating good performance of the materials or stacks tested inthese samples with respect to negative pressure transmission at thespecified heights and widths when wet.

Turning to FIG. 16F, the measured pressure differential of a set ofsample dressings of FIGS. 15H and 15I is depicted as a function of setnegative pressure with a 16 scc/minute leak rate. This set of sampledressings includes 410502, 410503, 410504, 410505, 410506, 411201 and411202. A subset of the sample dressings of FIGS. 15C and 15D is alsodepicted, including 347303, 347306, 347311, 347312, and 347313. Withrespect to the absorbent foam tested in sample 410503, the masking layertested in sample 410504, the prehydrated PVA foam tested in 410506 andthe stack containing a reticulated PU foam transmission layer withdimensions of 10 mm mean width and 13 mm mean height stack tested insample 411202, the corresponding plot lines demonstrate that thepressure differential exceeds −5 mmHg at least at one point across therange of negative pressure set points assessed, in line with theobservation made for this sample in the dry testing illustrated in FIGS.15H and 15I. With respect to the stack tested in sample 347313 and theabsorbent foam tested in sample 347312, the corresponding plot linesdemonstrate that the pressure differential exceeds −5 mmHg at least atone point across the range of negative pressure set points assessed. Asillustrated by the corresponding plot line an increase in the pressuredifferential was observed for sample 411201, a stack containing areticulated PU foam transmission layer with dimensions of 10 mm meanwidth and 11 mm mean height, at a set-point of −60 mmHg, whilst thisincreased pressure differential abated at higher negative pressure setpoints, it still remained above −5 mmHg at other negative pressure setpoints, the general trend being consistent with the observation made forthis sample in the dry testing illustrated in FIGS. 15H and 15I. Theplot lines of test data corresponding to sample dressings 347303,347306, 347311, 410502 and 410505 all remain close to the zero pressuredifferential axis, indicating good performance with respect to negativepressure transmission at the specified heights and widths for eachmaterial or stack.

FIG. 16G illustrates test results for the same set of sample dressingsdepicted in FIG. 16F, however using a 50 scc/minute leak rate. Theresults generally correspond to the results illustrated in FIG. 16F withtwo exceptions. The first exception was for the reticulated PU foamlayer with dimensions of 10 mm mean width and 5 mm mean height tested insample 410502. Whilst this sample of reticulated PU foam did not displaya significant increase in the measured pressure differential during wettesting with a 16 scc/minute leak rate it was observed that when theleak rate was set at 50 scc/minute and a negative pressure set point of−200 mmHg was applied the pressure differential reached −6.0 mmHgbreaching the acceptability criteria set. The second exception was forthe prehydrated PVA foam tested in sample 410506. As illustrated by thecorresponding plot line, an increase in the pressure differential wasobserved for the sample up to a set point of −60 mmHg, however adecrease in the pressure differential was observed between −100 mmHg and−140 mmHg, and after −140 mmHg the increase in the pressure differentialresumed. If the profiles for both leak rates are considered together,bearing in mind the sequential nature of running first with the 16scc/minute leak rate followed by the 50 scc/minute leak rate andincreasing negative pressure set point through each run, the profilescould be indicative of partial liquid clearance occurring during thetest. The plot lines of test data corresponding to sample dressings347303, 347306, 347311 and 410505 all remain close to the zero pressuredifferential axis, indicating good performance with respect to negativepressure transmission at the specified heights and widths for eachmaterial or stack

Turning now to FIG. 16H, a comparison graph illustrates the performanceof all samples, normalized to a width of 10 mm±1 mm, as a function ofset negative pressure with a 16 scc/minute leak rate when wet tested.FIG. 16I illustrates test results for the same set of sample dressingsdepicted in FIG. 16H, however using a 50 scc/minute leak rate.Accordingly, FIGS. 16H and 16I allow for relative comparison of sampleperformance at a standardized width across the samples. Similar to theother pressure differential charts discussed herein, suitabletransmission layer materials will demonstrate a pressure differentialaround or below approximately −5 mmHg at points across the range ofnegative pressure set points assessed.

FIG. 16J illustrates the pressure differential at a negative pressureset point of −200 mmHg and 50 scc/minute leak rate after subtraction ofpositive control for each of the width-normalized wet tested sampledressings of FIGS. 16H and 16I. Table 3, below, provides a scoringanalysis of the tested samples based on the information presented inFIG. 16J in order to provide a screen of the suitability of the variouspotential transmission layer materials. In all cases the samplescontained a transmission layer with mean width of 10 mm±1 mm and werebeing assessed over a 20 mm±1 mm path length. Scoring was appliedaccording to the following criteria:

-   -   (1) A marking of “✓” indicates that a pressure differential of        −5.0 mmHg or less was recorded. Materials marked with “✓”        provide the most suitable permeability to gas and liquid at the        specified widths and heights when exposed to compression due to        negative pressure.    -   (2) A marking of “        ” indicates that the criteria of (1) was not met and a pressure        differential of −25.0 or less was recorded.    -   (3) A marking of “        ” indicates that the criteria of (2) was not met and a pressure        differential of −160.0 mmHg or less was recorded. This can        correspond to delivery of at least −40 mmHg therapy against a        set point in the range −60 to −200 mmHg with an air leak of 50        scc/minute. In some scenarios, −40 mmHg can represent the        minimum clinically acceptable level of wound therapy.    -   (4) A marking of “        ” indicates that the criteria of (3) was not met and a pressure        differential of 160.1 mmHg or greater was recorded. This can        correspond to delivery of less than −40 mmHg therapy against a        set point in the range −60 to −200 mmHg with an air leak of 50        scc/minute. In some scenarios, delivery of less than −40 mmHg        can result in clinically unacceptable levels of wound therapy.

TABLE 3 Mean cross Mean Mean sectional height width area Legend No.Material(s) (mm) (mm) (mm2) Assessment 347201—ADL Libeltex BVBA,SlimCore TL4, triple 2 11 27 ✓ layered ADL, hydrophilic PET andbicomponent fibres, through air bonded web, 150 gsm 347303—Stack Stack:✓ Don & Low Ltd Non Wovens, PP non 0.4 15 6 woven fabric, thermallybonded, 70 gsm Baltex 7970, weft knitted polyester spacer 2 11 20 layerfabric, 210 gsm (smaller footprint than masking layer) 347304—super-Glatfelter Falkenhagen GmbH, 2 10 18

absorber MH460.101, multibonded airlaid nonwoven containingsuper-absorbent powder, laminated against cellulose tissue, 460 gsm347306—Stack Stack: ✓ Don & Low Ltd Non Wovens, PP non 0.4 14 6 wovenfabric, blue, thermally bonded, 70 gsm Glatfelter Falkenhagen GmbH, 2 1425 MH460.101, multibonded airlaid nonwoven containing super-absorbentpowder, laminated against cellulose tissue, 460 gsm GlatfelterFalkenhagen GmbH, 1 15 11 MH080.121, multibonded airlaid nonwoven Baltex7970, weft knitted polyester spacer 2 11 19 layer fabric, 210 gsm(smaller footprint than upper layers) 347311—Stack Stack: ✓ GlatfelterInc., DT360.100, thermally 3 14 46 bonded air-laid with super-absorbentpowder and cellulose fibres, 360 gsm Baltex 7970, weft knitted polyesterspacer 2 10 18 layer fabric, 210 gsm (smaller footprint than upperlayer) 347312— Smith & Nephew, Allevyn foam, from 10 10 99

Absorbent bulk, with a non-adhesive perforated Foam wound contact layer(WCL) laminated to the top and bottom surfaces (WCL is the same asapplied to the ProGuide Wound Contact Layer (WCL) surfaces) 347313—StackStack:

Glatfelter Inc., DT360.100, thermally 4 11 40 bonded air-laid withsuper-absorbent powder and cellulose fibres, 360 gsm Smith & Nephew,RENASYS-F Foam, 5 10 52 reticulated, open-cell, polyurethane foam349301—ADL Shalag Nonwovens, ST6CTPH90G, ADL, 2 10 24

90 gsm (longitudinal axis of the sample in line with the visuallypredominate fibre orientation of the distribution layer. Distributionlayer orientated next to top film) 349302—ADL Shalag Nonwovens,STAHTCT8OL, ADL, 1 11 16

80 gsm (Distribution layer orientated next to top film) 349303—ADLShalag Nonwovens, ST6CT8H65, ADL, 3 9 26

65 gsm (Distribution layer orientated next to top film) 349304—ADLShalag Nonwovens, ST6NT8H75, ADL, 4 10 44 ✓ 75 gsm (Distribution layerorientated next to top film) 349305—3D Apex Mills, 3D Spacer Fabric,DNB198A, 2 10 21 ✓ Spacer Fabric polyester, 270 gsm (Face with largerholes orientated next to top film.) 349306—3D Apex Mills, 3D SpacerFabric, DNB197, 6 10 60

Spacer Fabric polyester, 670 gsm 349307—3D Heathcote Fabrics Limited,SpaceTec, 2.5 3 10 25 ✓ Spacer Fabric mm gauge, polyester, 430 gsm (Facewith larger holes orientated next to top film.) 349308—3D HeathcoteFabrics Limited, SpaceTec, 3 3 10 30 ✓ Spacer Fabric mm gauge,polyester, 320 gsm (Face with larger holes orientated next to top film.)349309—3D Apex Mills, 3D Spacer Fabric, DNB22(6), 3 9 29 ✓ Spacer Fabricpolyester (Face with larger holes orientated next to top film.)349310—ADL Libeltex BVBA, DryWeb T28F, 1 10 14

monolayered AQL, hydrophilic PET and bicomponent fibres, through airbonded web, 50 gsm 349311—ADL Libeltex BVBA SlimCore TL4, triple 3 10 29✓ layered ADL, hydrophilic PET and bicomponent fibres, through airbonded web, 90 gsm 410502— Smith & Nephew, RENASYS-F Foam, 5 10 53

Reticulated reticulated, open-cell, polyurethane foam Foam 410503— Smith& Nephew, Allevyn foam, from 6 10 61

Absorbent bulk Foam 410504— Don & Low Ltd Non Wovens, PP non 0 10 5

Masking Layer woven fabric, blue, thermally bonded, 70 gsm 410505— Smith& Nephew, RENASYS-F Foam, 10 10 100 ✓ Reticulated reticulated,open-cell, polyurethane foam Foam 410506—PVA KCI, WhiteFoam, prehydratedopen cell 10 10 96

Foam PVA foam (prehydrated) 411201—Stack Glatfelter Inc., DT360.100,thermally 4 14 57 ✓ bonded air-laid with super-absorbent powder andcellulose fibres, 360 gsm Smith & Nephew, RENASYS-F Foam, 11 10 106reticulated, open-cell, polyurethane foam (smaller footprint than upperlayer) 411202—Stack Glatfelter Inc., DT360.100, thermally 4 15 57 ✓bonded air-laid with super-absorbent powder and cellulose fibres, 360gsm Smith & Nephew, RENASYS-F Foam, 13 10 131 reticulated, open-cell,polyurethane foam (smaller footprint than upper layer)

Table 4 illustrates the raw data used to generate the charts of FIGS.16A-16J.

TABLE 4 Leak rate (scc/min) Leak rate (scc/min) 16 50 Pressures (mmHg)Pressures (mmHg) 0 60 100 140 200 0 60 100 140 200 Ref Recorded dP(mmHg) Day 3: Negative Control 0 −66.8 −108.6 −150.8 >−200 PositiveControl 0.1 −3.3 −5.2 −7 −9.9 0.2 −3.4 −5.3 −7.1 −10 346604 0.1 −51.5−80.2 −105.1 −137.1 0.1 −47.2 −88.4 −118.5 −164.9 346605 −0.2 −5.7 −8.3−13.1 −19.1 0 −7.2 −12.2 −18.6 −30.4 346606 0.1 −3.6 −5.8 −10.3 −15 −0.1−4.4 −7.1 −10.3 −19.2 347304 0.1 −63.3 107.4 149.2 >−200 347201 −0.1 −4−6 −7.8 −10.7 0.1 −4 −6.1 −8.2 −11.5 Day 5 Negative Control 0.1 −62.8−104.2 −144.1 >−200 Positive Control 0.1 0.4 0.7 1 1.5 0 0.2 0.5 0.8 1.3349301 0.02 −1.9 −2.1 −2.3 −3.1 −0.2 −3.1 −3.7 −4.1 −5.3 349302 0.1 −0.9−1.1 −1.5 −2.4 0 −2.2 −2.7 −3.3 −4.8 349303 0 −0.8 −0.8 −1.2 −2.1 0.1−1.6 −2.2 −3 −5.1 349304 −0.1 −0.7 −0.6 −0.5 −0.2 0 0.9 −0.7 −1.2 −1.5349305 −0.1 0.1 −0.1 −0.4 −1.2 0 −0.8 −1.4 −1.8 −3.2 349306 0.1 −4.5−4.3 −3.5 −3 0 −10.5 −5.3 −8.5 −9.5 349307 0 −0.8 −0.2 −0.3 0.9 0.1 −0.7−0.2 0.7 1.3 349308 0.1 0.4 0.8 1.2 1.2 0 −0.5 −0.1 0.2 0.6 349309 −0.2−4.7 −3.4 0.9 −3.7 0 −0.2 −0.1 0 0 349310 0.2 −2 −2.2 −3 −3.8 0.1 −6.4−10.2 −10.4 −14.5 349311 0 0.6 0.9 1.1 −3.2 −0.2 −0.3 −0.4 −0.6 −0.9 Day6: Negative Control 0.1 −62.7 −103.7 −143.8 >−200 Positive Control 0.10.1 0.1 0.1 −0.1 0.3 0.6 0.5 0.5 0.3 410503 1.9 −40 −75 −116 −178 2.2−46 −79 −117 −178 410506 −0.2 −30 −30 −54 −102 1.2 −31 −6 −9.5 −40 Day7: Negative Control 1.4 −60.6 −101.4 −141.2 >−200 Positive Control 1.30.5 0.3 0.2 0 0.5 0.3 0.2 0.1 −0.1 410502 2 1.7 1.4 0.9 −0.2 2.2 0.7−0.2 −1.4 −4.4 410504 2.3 −7 −10 −14.5 −20.2 2.4 −23 −34 −41.6 −55410505 1.8 0.8 −0.1 1 −0.2 2.3 1.7 1.4 0.9 −0.1 347303 0.9 1.7 1.6 1.41.1 2 1.2 1.3 1.1 0.8 347306 2 0.4 0.5 0.3 0.1 2.1 −1.4 −0.3 −0.3 −0.9347311 2.5 1.3 1.2 1 0.6 2.2 1.6 1.4 1.1 0.2 347312 2.2 −59 −97 −120−173 2.4 −53 −83 −112 −165 347313 2.3 −9 −14.7 −21.4 −28 2.3 −11 −17.1−24 −29 411201 1.7 −20 −4 −7.8 −10 1.5 −32 −6 −8 −11 411202 1.8 −4.3−4.5 −7 −9 2 −6 −5 −6 −8

As indicated by the test results illustrated in FIGS. 16A-16J and thematerial specifications of Table 1, a dressing implementing thereticulated foam or SlimCore TL4 as a transmission layer will experiencelow negative pressure differentials across bridging portions with widthsas low as approximately 3 mm for the reticulated foam and 11 mm for theSlimCore TL4, even when fluid is introduced to the dressing system.Although spacer material such as Baltex 3D weft-knit fabric was not wettested, this material is expected to produce clinically appropriate testresults of a pressure differential in the range of −5 mmHg to 0 mmHg ata −200 mmHg pressure set point using the described test model or asimilar test model. Accordingly, open-cell reticulated foam, SlimCoreTL4, spacer material, and similar woven and non-woven materials aresuitable transmission layers for bridging portions of dressings. Suchmaterials are suitable in some embodiments for the bridging portionsdescribed above or below. Although additional layers can be used inbridging portions in some embodiments, for example a masking layer orcombinations of transmission layers, bridging portions will transmitclinically appropriate negative pressure ranges using just onetransmission layer satisfying the testing criteria.

The test results of FIGS. 15A-16J highlight the interplay betweenmaterial properties, cross sectional dimensions (minimum width andheight) and the effect of adjacent materials within the dressing on theclinically or therapeutically suitable permeability of a sample to gasand liquid while under compression due to negative pressure. Forexample, the reticulated foam alone typically can be a suitable materialfor use as a transmission layer, however when combined with an absorbentlayer over the reticulated foam, at heights below approximately 10 mmthe foam began to fail to deliver therapeutically suitable negativepressure.

VIII. Overview of Additional Bridged Dressing Embodiments

FIG. 17A illustrates a plan view of a trimmable dressing 1600 embodimentwherein the number of layers present in the bridging portions 1620 ofthe dressing is less than in an absorbent pad portion 1630 or asecondary absorbent portion 1650 of the dressing. FIG. 17B illustrates aside view of the dressing 1600. Accordingly, the overall height of thedressing is reduced at the bridging portions 1620 relative to theabsorbent pad portions. In some embodiments, the dressing can alsoreduce in width at the bridging portions relative to the absorbent padportions. The dressing 1600 also includes a port 1640 for delivery ofnegative pressure.

The dressing 1600 includes a spacer layer 1662 in the absorbent padportion 1630 and secondary absorbent portions 1650. An ADL 1664 extendsacross the length of the dressing through the absorbent pad portion1630, secondary absorbent portions 1650, and bridging portions 1620. TheADL 1664 satisfies the testing criteria specified above and is capableof negative pressure transmission through the bridging portions 1620. Insome implementations of the trimmable dressing 1600, the ADL 1664 may beconstructed from an ADL material that is easier to cut than a spacermaterial, and may be accordingly selected for the bridging portions1620. In other embodiments, the spacer layer 1662 may extend across thelength of the dressing in addition to or instead of the ADL 1664.

In the absorbent pad portion 1630 and secondary absorbent portions 1650,the dressing 1600 includes an absorbent layer 1666 and masking layer1668. In some embodiments, the masking layer 1668 may extend across thebridging portions 1620, and may include holes, windows, perforations, orother visual indicators for indicating to a user where to cut thedressing. For example, perforations may be arranged in a dashed ordotted line configuration along a location within a bridging portion1620, revealing a contrasting color of the ADL 1664 beneath the maskinglayer 1668 to visually indicate a potential location for trimming thedressing 1600. This approach could be extended to include designs andsymbology such as the symbol of a pair of scissors and/or a dotted line,or notches/chevron on each side of the masking layer, letteringindicating a “cut here” location, or the like. The interior layers 1662,1664, 1666, 1668 are positioned between a wound contact layer 1672 and atop film layer 1674 that are sealed together around a perimeter 1610,for example a perimeter of approximately 2.5 cm in some embodiments.

This layer arrangement can provide the advantage of increasedflexibility at the bridging points during wear of the dressing, easycutting with scissors (or other means) during fitting and shaping of thedressing to a wound site, and easier sealing of cut portions. Thereduced height of the bridging portions provides a smaller gap thatneeds to be sealed. Cut or trimmed portions can be sealed with asealant, a sealing strip as depicted in FIGS. 14A-14D, a flexibleadhesive drape, or other sealing means. In addition, use of differenttop layers in the absorbent pad portions compared to the bridgingportions can result in a color coded dressing, making the cuttinglocations clear to the user. Such a dressing can be convenient for usealong long incision wounds where the length varies from patient topatient, for example incisions resulting from abdominoplasty procedures,as the dressing can be trimmed according to specific patient needs.

FIG. 18 illustrates one embodiment of a dressing 1700 suitable forplacement on a heel. The dressing 1700 includes a sealed perimeter 1710,bridging portion 1720, central absorbent pad 1730, and a port 1740 fortransmission of negative pressure to the dressing 1700, and optionallyincludes two secondary absorbent pads 1750. The center portion 1740 canbe applied to a patient's heel such that the top half is on the back ofthe heel and the bottom half folds under the heel. The “wings” includingthe optional secondary absorbent pads 1750 and the surrounding bridgingand perimeter portions can then be folded around each side of thepatient's ankle. Cushioning is important with heel dressings to protectthe malleolus for typical users (i.e. diabetic heel ulcer patients).Optionally, additional secondary absorbent pad portions 1750 can bepositioned in dressing 1700 in order to be located over each malleoluswhen applied in order to provide cushioning and increase the overallabsorbency of the dressing. The spacer could optionally be included inthe secondary absorbent pad portions 1750 for additional cushioning. Insome embodiments, the secondary absorbent pad portions 1750 can includea spacer layer and an ADL without an absorbent layer.

The central absorbent pad 1730 and optional secondary absorbent pads1750 can include an absorbent layer as discussed herein, and can alsoinclude a layered configuration as disclosed herein, for example withreference to FIGS. 4A-4D. The bridging portions 1720 can include anymaterial having negative pressure transmission properties that satisfythe testing criteria described above with respect to FIGS. 15A-16C, forexample a 3D-knit spacer layer, woven ADL (such as Libeltex SlimcoreTL4), or open-cell reticulated foam.

Fitting a composite NPWT dressing to a heel has been a significantchallenge due to conformability to this highly curved area, especiallygiven the good seal required to exclude leaks from the system. Folding athicker, composite dressing around a highly nonplanar surface such as aheel often results in leaks in the dressing system. The flexible bridgeportions 1720 surrounding the main pad portion 1730 and optionalsecondary pad portions 1750 as illustrated in FIG. 18 can unlock thisneeded conformability and allow negative pressure therapy to besuccessfully applied using a composite heel dressing.

FIG. 19 illustrates an embodiment of an extremity dressing 1800. Theextremity dressing 1800 can have a multi-layered absorbent pad 1830 in acenter area, here depicted as a circular shape (though others arepossible in other embodiments), and three bridge portions 1820 extendingaway from the center absorbent pad. The bridge portions 1820 aresurrounded by a sealed perimeter 1810, for example of a wound contactlayer and a top film layer. A port 1840 can be attached to providenegative pressure to the dressing 1800. The bridge portions 1820 caninclude Libeltex SlimCore ADL in some embodiments. Any of the materialsdescribed above with respect to FIGS. 4A-4D and FIGS. 9A-13 can besuitable for use in dressing 1800. Materials used in bridge portions1820 may be selected to satisfy the testing criteria described abovewith respect to FIGS. 15A-16C.

In other embodiments, two, four, or more bridge portions 1820 can extendaway from the center pad. The bridge portions 1820 may be evenly spacedaround a circumference of the dressing, as illustrated, or can belocated asymmetrically as needed for providing a dressing for specificwound types. One or more bridge portions 1820 can be trimmed or cut offaccording to the wound shape. Cut or trimmed portions can be sealed witha sealant, a sealing strip as depicted in FIGS. 14A-14D, a flexibleadhesive drape, or other sealing means.

The bridge portions 1820 can deliver negative pressure to the centerabsorbent pad 1830 of the dressing, which may need to be weight bearing.Accordingly, port 1840 can be located on one or more of the bridgeportions 1820, in some embodiments. A spacer layer in the centerabsorbent pad can provide additional cushioning for the user and alsoserve to maintain an air path even if that section of the dressing isweight bearing.

Such a dressing configuration can provide for therapeutic advantagescompared to previous dressings in certain circumstances involving largewounds on a patient's extremity, for example following amputation byplacement at the distal end of the residual limb. The radially extendingarms can extend over incision wounds, and in some embodiments caninclude additional absorbent material over some or all of the radiallyextending arm. Wounds on nonplanar body areas with tight geometries canalso benefit from treatment with the dressing of FIG. 19 .

FIG. 19 illustrates a wound dressing having a center absorbent padsurrounded by a skirt portion. The skirt portion includes at least onetransmission layer, and can include other layers in some embodiments,such as an obscuring layer. The center absorbent pad can include thetransmission layer as well as an absorbent layer. The skirt portionsurrounding the pad portion can allow for delivery of negative pressureover a wide area with liquid stored locally in the center of thedressing. In addition, the skirt portion allows for dynamic shaping ofthe dressing to conform to a patient's wound while providing arelatively small edge gap for sealing at the cut portions. Cut ortrimmed portions can be sealed with a sealant, a sealing strip asdepicted in FIGS. 14A-14D, a flexible adhesive drape, or other sealingmeans.

FIGS. 20A and 20B illustrate two embodiments of dressings 1900, 1950having a sealed perimeter 1910 surrounding a bridge or skirt portion1920, the skirt portion 1920 surrounding an absorbent pad portion 1930having a port 1940. The port 1940 can be repositioned in any area overthe skirt portion 1920 or absorbent pad portion 1930 in otherembodiments. The skirt portion 1920 can function like a bridge portionillustrated in many of the dressings described above, that is totransmit fluid and negative pressure across the dressing 1900, 1950. Insome embodiments, multiple absorbent pad portions can be connected by askirt portion. The absorbent pad portion 1930 can include an absorbentlayer as discussed herein, and can also include a layered configurationas disclosed herein, for example with reference to FIGS. 4A-4D. Any ofthe materials described above with respect to FIGS. 4A-4D and FIGS.9A-13 can be suitable for use in dressing 1900.

The skirt portion 1920 may be constructed so as to minimize a height ofthe dressing 1900, 1950 at the skirt portion 1920, and therefore adistance to be sealed when the skirt portion 1920 is trimmed. Forexample, the skirt portion can include just one layer in someembodiments, the skirt portion layer selected based on negative pressuretransmission properties. The skirt portion 1920 can include any materialhaving negative pressure transmission properties that satisfy thetesting criteria described above with respect to FIGS. 15A-16C, forexample a 3D-knit spacer layer, woven ADL (such as Libeltex SlimcoreTL4), or open-cell reticulated foam.

Advantageously, the large skirt portion 1920 surrounding the absorbentpad portion 1930 allows the dressing 1900. 1950 to be trimmed to conformto the shape of a wound, even for irregularly shaped wounds, withoutlosing the ability to transmit negative pressure across the dressing.Cut or trimmed portions can be sealed with a sealant, a sealing strip asdepicted in FIGS. 14A-14D, a flexible adhesive drape, or other sealingmeans.

Another dressing embodiment, not illustrated, can include a plurality ofcell or main portions connected by a plurality of bridging portions. Thebridging portions can have a smaller width, height, or both relative tosurrounding cell portions. In some embodiments, a minimum bridge widthcan be 1 mm (or approximately 1 mm). The dressing can include anoptional wound contact layer and a cover layer sealed together around aperimeter. Between the wound contact layer and the cover layer,open-cell foam, for example a reticulated foam, can extend through thecell portions and bridge portions. The foam can be continuous orassembled from discrete portions sized to fit within the cell and bridgeportions. Certain embodiments of the dressing may or may not include anabsorbent material, and may include a canister or other collectionvessel external to the dressing for collecting wound exudate removedfrom the wound.

Referring now to FIG. 21 , another embodiment of a trimmable dressing2100 is illustrated. The dressing may comprise, from bottom to top, anoptional wound contact layer (not shown), a transmission layer and/orADL over the wound contact layer, a plurality of absorbent cells overthe transmission layer and/or, and a cover layer over the plurality ofabsorbent cells. As illustrated in FIG. 21 , one embodiment of thedressing includes a border 2105, a generally rectangular transmissionlayer 2110, a number of absorbent cells 2115, a port 2120, and a conduit2125 for connection of the dressing 2100 to a source of negativepressure. The border 2105 can include a cover layer as described abovesealed to the healthy skin of a patient surrounding a wound in oneexample, or can include a cover layer sealed to a wound contact layer asdescribed above. This cover layer may extend over the plurality ofabsorbent cells 2115. The port 2120 and conduit 2125 can be configuredfor transmitting negative pressure to the dressing 2100 from a source ofnegative pressure when in use.

The transmission layer 2110 can extend across the entire central padarea, and can be any material described herein, or the equivalent,having suitable permeability to gas and liquid at a minimum heightand/or width. By having the transmission layer 2110 extend across thecentral pad area rather than only being placed in bridging areas, a morecomfortable distribution of pressure over the patient's therapy site canbe achieved. Such pressure distribution can be considered both from thepoint of view of NPWT delivery and from the point of view of protectingfriable skin, where (depending on the design of the dressing) blisteringcan be caused at pad edges. Therefore, a continuous transmission layercan, in some embodiments, minimize the number of pad edges (i.e. using acontinuous lower layer) providing an advantage for pressuredistribution.

A number of absorbent cells 2115 can be included above the transmissionlayer 2110, and can be any of the absorbent materials described herein,for example with respect to FIGS. 3A-4D and 11A-11B. By cutting thedressing 2100 along the areas of transmission layer 2110 betweenadjacent cells 2115, the dressing 2100 can be adaptively sized tocorrespond to the shape of a patient's wound. The dressing 2100 can besealed along cut portions by one or more of re-sealing of the coverlayer and wound contact layer, through a sealant adhesive, and sealingstrips as described in FIGS. 14A-14D in various embodiments.

Although the absorbent cells 2115 are illustrated as being triangular inshape, other variations can include circular, oval, square, rectangular,hexagonal, or other shaped cells. Further, although the absorbent cells2115 are illustrated as being discrete portions of absorbent material,in other embodiments the absorbent cells 2115 can be connected bybridging portions.

IX. Overview of Additional Layer Materials

FIGS. 22A through 22E illustrate an example of Libeltex DryWeb T28F thatcan be suitable for use as acquisition distribution layer material (ADL)material which may be used in any of the dressing embodiments describedabove, and which may also be used in any of the port or fluidicconnector embodiments described above. To those versed in the art ofacquisition distribution layers, also known as “surge layers,” it wouldbe obvious that other ADL materials may be used to achieve a similareffect of laterally wicking fluid. Suitable ADL materials can allow forfull capacity use. Such ADL layers may be composed of multiple fibertypes and be complex in structure and design.

FIG. 22A illustrates a backscatter scanning electron microscope (SEM)plan view of a sample portion of ADL material at 70× magnification. FIG.22B illustrates an SEM plan view of the ADL material at 140×magnification, and FIG. 21C illustrates an SEM plan view of the ADLmaterial at 500× magnification. As illustrated by FIGS. 22A-22C, the ADLmaterial can comprise a number of non-woven fibers extending at leastpartially horizontally (that is, parallel to the plane of the top andbottom surfaces of the material) for laterally/horizontally wickingfluid through the ADL material.

FIG. 22D illustrates an SEM cross sectional view of the ADL material at500× magnification, and FIG. 22E illustrates an SEM cross sectional viewof the ADL material at 1550× magnification. In the illustratedembodiment, the ADL material may consist of a mix of multiple fibertypes. One may be a roughly cylindrical fiber. Another fiber may be arelatively flatter fiber having a centrally-located negative space.Another fiber may be a multi-component fiber that has at least one innercore fiber, in some embodiments three inner core fibers as in theillustrated sample, and an outer layer surrounding the inner core.

FIGS. 23A through 23E illustrate an example of Libeltex SlimCore TL4that can be suitable for use as acquisition distribution layer material.FIG. 23A illustrates an SEM cross sectional view of a sample portion ofADL material at 50× magnification. The ADL material can include an upperlayer 2305 and a lower layer 2310 having different densities, lofts, andthicknesses. For example, the upper layer 2305 can comprise a moredense, less lofted fiber configuration and can be approximately 730 μmthick in some embodiments. The lower layer 2310 can comprise a lessdense, more lofted fiber configuration and can be approximately 1200 μmthick in some embodiments. FIG. 23B illustrates an SEM plan view of asample portion of the denser upper layer 2305 at 70× magnification, andFIG. 23C illustrates an SEM plan view of a sample portion of the denserupper layer 2305 at 250× magnification. FIG. 23D illustrates an SEM planview of a sample portion of the more lofted lower layer 2310 at 70×magnification, and FIG. 23E illustrates an SEM plan view of a sampleportion of the more lofted lower layer 2310 at 250× magnification. Asillustrated by FIGS. 23A-23E, the upper and lower layers 2305, 2310 ofthe ADL material can comprise different densities of a number ofnon-woven fibers extending at least partially horizontally (that is,parallel to the plane of the top and bottom surfaces of the material)for laterally/horizontally wicking fluid through the ADL material.

As illustrated by FIGS. 22A-23E, the non-woven fibers of the variousillustrated ADL materials can extend more in a horizontal direction thanin a vertical direction to aid in lateral wicking of fluids through thematerial. In some embodiments, a majority of the fiber volume may extendhorizontally or substantially or generally horizontally. In anotherembodiment, 80%-90% (or approximately 80% to approximately 90%) or moreof the fiber volume may extend horizontally, or substantially orgenerally horizontally. In another embodiment, all or substantially allof the fiber volume may extend horizontally, or substantially orgenerally horizontally. In some embodiments, a majority, 80%-90% (orapproximately 80% to approximately 90%) of the fibers or more, or evenall or substantially all of the fibers, span a distance perpendicular tothe thickness of the ADL material (a horizontal or lateral distance)that is greater than the thickness of the ADL material. In someembodiments, the horizontal or lateral distance spanned by such fibersis 2 times (or about 2 times) or more, 3 times (or about 3 times) ormore, 4 times (or about 4 times) or more, 5 times (or about 5 times) ormore, or 10 times (or about 10 times) or more the thickness of the ADLmaterial. The orientation of such fibers may promote lateral wicking offluid through the ADL material. This may more evenly distribute fluidsuch as wound exudate throughout the ADL material. In some embodiments,the ratio of the amount of fluid wicked laterally across the ADLmaterial to the amount of fluid wicked vertically through the ADLmaterial under negative pressure may be 2:1 or more, or approximately2:1 or more, or may be up to 10:1 or more, or approximately 10:1 ormore, in some embodiments.

X. Terminology

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example describedherein unless incompatible therewith. All of the features disclosed inthis specification (including any accompanying claims, abstract anddrawings), and/or all of the steps of any method or process sodisclosed, may be combined in any combination, except combinations whereat least some of such features and/or steps are mutually exclusive. Theprotection is not restricted to the details of any foregoingembodiments. The protection extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of protection. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made. Those skilled in the art willappreciate that in some embodiments, the actual steps taken in theprocesses illustrated and/or disclosed may differ from those shown inthe figures. Depending on the embodiment, certain of the steps describedabove may be removed, others may be added. Furthermore, the features andattributes of the specific embodiments disclosed above may be combinedin different ways to form additional embodiments, all of which fallwithin the scope of the present disclosure.

Although the present disclosure includes certain embodiments, examplesand applications, it will be understood by those skilled in the art thatthe present disclosure extends beyond the specifically disclosedembodiments to other alternative embodiments and/or uses and obviousmodifications and equivalents thereof, including embodiments which donot provide all of the features and advantages set forth herein.Accordingly, the scope of the present disclosure is not intended to belimited by the specific disclosures of preferred embodiments herein, andmay be defined by claims as presented herein or as presented in thefuture.

What is claimed is:
 1. A wound treatment apparatus comprising: a wounddressing configured to be positioned over a wound site, the wounddressing comprising: a material layer comprising a plurality of cellsdefined by predefined cuts along a first surface thereof, wherein eachcell of the plurality of cells is at least partially separated from anadjacent cell along a majority of every side of each said cell thatfaces an adjacent cell, wherein the plurality of cells compriserectangular-shaped cells, wherein the plurality of cells of the materiallayer are configured to allow the material layer to conform to anon-planar surface; a backing layer over the material layer andcomprising at least one orifice; a wound contact layer beneath thematerial layer and sealed to the backing layer; and a fluidic connectorpositioned over the at least one orifice configured to provide negativepressure through the wound dressing to the wound site; wherein each cellis partially connected to an adjacent cell of the plurality of cells bybridging portions that together with the plurality of cells form asingle continuous material layer; wherein the bridging portions have asmaller height than surrounding cell portions.
 2. The wound treatmentapparatus of claim 1, wherein the plurality of cells are arranged in aregularly repeating grid pattern.
 3. The wound treatment apparatus ofclaim 2, wherein the plurality of cells comprise square-shaped cells. 4.The wound treatment apparatus of claim 1, wherein the plurality of cellscomprise cells having a shape selected from the group consisting of asquare, rectangle, circle, pentagon, hexagon, octagon, and triangle. 5.The wound treatment apparatus of claim 1, wherein the plurality of cellscomprise cells having a same shape and a same size.
 6. The woundtreatment apparatus of claim 1, wherein the predefined cuts comprisecuts parallel to a first orientation.
 7. The wound treatment apparatusof claim 6, wherein the predefined cuts further comprise cuts parallelto a second orientation, the second orientation perpendicular to thefirst orientation.
 8. The wound treatment apparatus of claim 1, whereineach cell of the plurality of cells is connected to an adjacent cell ofthe plurality of cells along every side of each said cell that faces aside of an adjacent cell.
 9. The wound treatment apparatus of claim 1,wherein the material layer comprises an absorbent layer.
 10. The woundtreatment apparatus of claim 1, wherein the material layer comprises afoam layer.
 11. The wound treatment apparatus of claim 1, furthercomprising a transmission layer beneath the material layer.
 12. A woundtreatment apparatus comprising: a wound dressing configured to bepositioned over a wound site, the wound dressing comprising: a foamlayer comprising a plurality of cells arranged in a regularly repeatingrectangular-shaped grid pattern, wherein each cell of the plurality ofcells is partially connected to an adjacent cell along every side ofeach said cell that faces a side of an adjacent cell, and wherein eachcell of the plurality of cells is physically separated from an adjacentcell along a majority of every side of each said cell that faces a sideof an adjacent cell, wherein the plurality of cells of the foam layerare configured to allow the foam layer to conform to a non-planarsurface; a backing layer over the foam layer and comprising at least oneorifice; a wound contact layer beneath the foam layer and sealed to thebacking layer; and a fluidic connector positioned over the at least oneorifice configured to provide negative pressure through the wounddressing to the wound site; wherein each cell is partially connected toan adjacent cell of the plurality of cells by bridging portions thattogether with the plurality of cells form a single continuous foamlayer; wherein the bridging portions have a smaller height thansurrounding cell portions.
 13. The wound treatment apparatus of claim12, wherein the plurality of cells are arranged in a regularly repeatingsquare-shaped grid pattern.
 14. The wound treatment apparatus of claim12, wherein the bridging portions have a smaller width than surroundingcell portions.
 15. A wound treatment apparatus comprising: a wounddressing configured to be positioned over a wound site, the wounddressing comprising: a material layer comprising a plurality of cells,wherein each cell of the plurality of cells is at least partiallyseparated from an adjacent cell along every side of each said cell thatfaces an adjacent cell, wherein the plurality of cells of the materiallayer are configured to allow the material layer to conform to anon-planar surface; a backing layer over the material layer andcomprising at least one orifice; a wound contact layer beneath thematerial layer and sealed to the backing layer; and a fluidic connectorpositioned over the at least one orifice configured to provide negativepressure through the wound dressing to the wound site; wherein each cellis partially connected to an adjacent cell of the plurality of cells bybridging portions that together with the plurality of cells form asingle continuous material layer; wherein the bridging portions have asmaller height than surrounding cell portions.
 16. The wound treatmentapparatus of claim 15, wherein the plurality of cells are arranged in aregularly repeating pattern.
 17. The wound treatment apparatus of claim16, wherein the plurality of cells comprise cells having a same size andthe same polygonal shape.